ci: use shared gh-actions/actions/contract-tests action (#164)

**Requirements**

- [x] I have added test coverage for new or changed functionality
- [x] I have followed the repository's [pull request submission
guidelines](../blob/main/CONTRIBUTING.md#submitting-pull-requests)
- [x] I have validated my changes against all supported platform
versions

**Related issues**

N/A — CI-only change.

**Describe the solution you've provided**

Replace the local `.github/actions/contract-tests` action with the
shared
`launchdarkly/gh-actions/actions/contract-tests@contract-tests-v1`
action.

The local action accepted a `token` input but never forwarded it, so
`GITHUB_TOKEN` was not used when downloading the contract test harness
(leading to potential rate limiting). The shared action properly passes
the token both as an `Authorization` header on the curl request and as
the `GITHUB_TOKEN` env var for the downloader script.

Since the shared action only handles downloading and running the harness
(not building/starting the test service), the build and start steps are
now explicit workflow steps.

**Describe alternatives you've considered**

Could have fixed the local action to forward the token to the Makefile,
but using the shared action is more maintainable and consistent with
other SDK repos.

**Additional context**

Both `java-server-sdk.yml` and `nightly-contract-tests.yml` are updated.
The Makefile is left unchanged so local development workflows still
work."

Link to Devin session:
https://app.devin.ai/sessions/02984ba491764e598f041b70041206ba
Requested by: @kinyoklion

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> CI-only workflow changes; no application runtime or SDK library
behavior is modified.
> 
> **Overview**
> Removes the repo-local **contract-tests** composite action and wires
**java-server-sdk** and **nightly-contract-tests** workflows to
**`launchdarkly/gh-actions/actions/contract-tests@contract-tests-v1`**.
> 
> Contract testing now **explicitly** runs `make build-contract-tests`
and `make start-contract-test-service-bg` before the harness. **v2** and
**v3** harness runs are separate steps (v3 pinned to `v3.0.0-alpha.6`),
each passing **`GITHUB_TOKEN`**, suppression files via
**`extra_params`**, and shared options like **`enable_persistence_tests:
'false'`**. Nightly v3 still passes **`-enable-long-running-tests`**
through **`extra_params`**.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
3580edb. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: kinyoklion

.github/actions/contract-tests/action.yml

@@ -37,11 +37,34 @@ jobs:
           workspace_path: 'lib/sdk/server'
           java_version: 8
 
-      - name: Contract Tests
-        uses: ./.github/actions/contract-tests
+      - name: Build Contract Test Service
+        shell: bash
+        run: make build-contract-tests -C lib/sdk/server
+
+      - name: Start Contract Test Service
+        shell: bash
+        run: make start-contract-test-service-bg -C lib/sdk/server
+
+      - name: Contract Tests (v2)
+        uses: launchdarkly/gh-actions/actions/contract-tests@contract-tests-v1
         with:
-          workspace_path: 'lib/sdk/server'
+          test_service_port: '8000'
+          token: ${{ secrets.GITHUB_TOKEN }}
+          debug_logging: 'true'
+          stop_service: 'false'
+          enable_persistence_tests: 'false'
+          extra_params: '-skip-from=lib/sdk/server/contract-tests/test-suppressions.txt'
+
+      - name: Contract Tests (v3)
+        uses: launchdarkly/gh-actions/actions/contract-tests@contract-tests-v1
+        with:
+          test_service_port: '8000'
+          version: 'v3.0.0-alpha.6'
+          branch: 'v3.0.0-alpha.6'
           token: ${{ secrets.GITHUB_TOKEN }}
+          debug_logging: 'true'
+          enable_persistence_tests: 'false'
+          extra_params: '-skip-from=lib/sdk/server/contract-tests/test-suppressions-fdv2.txt'
 
   test-packaging:
     runs-on: ubuntu-latest

.github/workflows/java-server-sdk.yml

@@ -29,12 +29,34 @@ jobs:
           workspace_path: 'lib/sdk/server'
           java_version: 8
 
-      - name: Contract Tests (with long-running tests)
-        uses: ./.github/actions/contract-tests
+      - name: Build Contract Test Service
+        shell: bash
+        run: make build-contract-tests -C lib/sdk/server
+
+      - name: Start Contract Test Service
+        shell: bash
+        run: make start-contract-test-service-bg -C lib/sdk/server
+
+      - name: Contract Tests (v2)
+        uses: launchdarkly/gh-actions/actions/contract-tests@contract-tests-v1
         with:
-          workspace_path: 'lib/sdk/server'
+          test_service_port: '8000'
+          token: ${{ secrets.GITHUB_TOKEN }}
+          debug_logging: 'true'
+          stop_service: 'false'
+          enable_persistence_tests: 'false'
+          extra_params: '-skip-from=lib/sdk/server/contract-tests/test-suppressions.txt'
+
+      - name: Contract Tests v3 (with long-running tests)
+        uses: launchdarkly/gh-actions/actions/contract-tests@contract-tests-v1
+        with:
+          test_service_port: '8000'
+          version: 'v3.0.0-alpha.6'
+          branch: 'v3.0.0-alpha.6'
           token: ${{ secrets.GITHUB_TOKEN }}
-          test_harness_params_v3: '-enable-long-running-tests'
+          debug_logging: 'true'
+          enable_persistence_tests: 'false'
+          extra_params: '-skip-from=lib/sdk/server/contract-tests/test-suppressions-fdv2.txt -enable-long-running-tests'
 
   notify-slack-on-failure:
     runs-on: ubuntu-latest