fix(provider): show controller-runtime logs with --debug

[henrysachs]

Why

--debug should give controller-runtime a real logger, but its logs never appear. main sets a discard logger first and the debug logger second. controller-runtime keeps only the first SetLogger call, so the discard logger always wins. This has been the case since v0.9.0.

What changed

• main calls ctrl.SetLogger once. It passes the debug logger with --debug and the discard logger otherwise.

Scope

• Without --debug nothing changes. controller-runtime still gets the discard logger.
• Log levels and the provider's own logger do not change.

Blast Radius

Only --debug output changes. It now includes controller-runtime lines, such as controller start-up, and errors logged through the manager logger, such as gated controller setup failures.

Verification

• I ran the provider locally against a kind cluster. With --debug, master printed no controller-runtime lines. This branch printed 81 "Starting Controller" and 83 "Starting EventSource" lines. Without --debug, both printed nothing.
• With --debug, this branch also printed a gate setup error that master hides: "controller with name providerconfig/providerconfig.gitlab.m.crossplane.io already exists". fix(config): register ClusterProviderConfig controller on SafeStart #452 fixes that error.
• go build ./..., go test ./pkg/... ./cmd/..., golangci-lint run ./..., and go generate -tags generate ./apis/... ./pkg/... (no diff) pass.

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review. I ran the checks above instead.