Enable usestdlibvars linter and fix all violations (#4978)

## Summary
- Enable the `usestdlibvars` golangci-lint linter, which detects places
where Go standard library constants should be used instead of literal
values
- Auto-fixed all violations: HTTP method strings (`"GET"`, `"POST"`,
etc.) replaced with `http.Method*` constants, and HTTP status codes
(`404`, `409`) replaced with `http.Status*` constants

## Test plan
- [x] `make checks fmt lint` passes
- [x] All unit tests pass (5025 tests)
- [x] No new acceptance test failures

Author: denik

.golangci.yaml

@@ -20,6 +20,7 @@ linters:
     - copyloopvar
     - forbidigo
     - depguard
+    - usestdlibvars
   settings:
     depguard:
       rules:

bundle/direct/dresources/postgres_endpoint.go

@@ -3,6 +3,7 @@ package dresources
 import (
 	"context"
 	"errors"
+	"net/http"
 	"strings"
 	"time"
 
@@ -180,7 +181,7 @@ func (r *ResourcePostgresEndpoint) DoDelete(ctx context.Context, id string) erro
 		if err != nil {
 			// Check if this is a reconciliation in progress error
 			var apiErr *apierr.APIError
-			if errors.As(err, &apiErr) && apiErr.StatusCode == 409 &&
+			if errors.As(err, &apiErr) && apiErr.StatusCode == http.StatusConflict &&
 				strings.Contains(apiErr.Message, "reconciliation") {
 				// Check if we've exceeded the timeout
 				if time.Now().After(deadline) {

cmd/bundle/generate/alert.go

@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"errors"
 	"fmt"
+	"net/http"
 	"os"
 	"path"
 	"path/filepath"
@@ -81,7 +82,7 @@ After generation, you can deploy this alert to other targets using:
 		if err != nil {
 			// Check if it's a not found error to provide a better message
 			var apiErr *apierr.APIError
-			if errors.As(err, &apiErr) && apiErr.StatusCode == 404 {
+			if errors.As(err, &apiErr) && apiErr.StatusCode == http.StatusNotFound {
 				return fmt.Errorf("alert with ID %s not found", alertID)
 			}
 			return err

cmd/labs/github/github.go

@@ -56,15 +56,15 @@ func getPagedBytes(ctx context.Context, method, url string, body io.Reader) (*pa
 		url = strings.Replace(url, gitHubUserContent, uco, 1)
 	}
 	log.Tracef(ctx, "%s %s", method, url)
-	req, err := http.NewRequestWithContext(ctx, "GET", url, body)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, body)
 	if err != nil {
 		return nil, err
 	}
 	res, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return nil, err
 	}
-	if res.StatusCode == 404 {
+	if res.StatusCode == http.StatusNotFound {
 		return nil, ErrNotFound
 	}
 	if res.StatusCode >= 400 {

experimental/ssh/internal/client/client.go

@@ -439,7 +439,7 @@ func getServerMetadata(ctx context.Context, client *databricks.WorkspaceClient,
 	}
 	metadataURL := fmt.Sprintf("%s/driver-proxy-api/o/%d/%s/%d/metadata", client.Config.Host, workspaceID, effectiveClusterID, wsMetadata.Port)
 	log.Debugf(ctx, "Metadata URL: %s", metadataURL)
-	req, err := http.NewRequestWithContext(ctx, "GET", metadataURL, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, metadataURL, nil)
 	if err != nil {
 		return 0, "", "", err
 	}

experimental/ssh/internal/client/websockets.go

@@ -15,7 +15,7 @@ func createWebsocketConnection(ctx context.Context, client *databricks.Workspace
 		return nil, fmt.Errorf("failed to get proxy URL: %w", err)
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create request: %w", err)
 	}

libs/appproxy/appproxy_test.go

@@ -19,7 +19,7 @@ const (
 )
 
 func sendTestRequest(t *testing.T, url, path string) (int, []byte) {
-	req, err := http.NewRequest("GET", url+path, bytes.NewBufferString("{'test': 'value'}"))
+	req, err := http.NewRequest(http.MethodGet, url+path, bytes.NewBufferString("{'test': 'value'}"))
 	require.NoError(t, err)
 	req.Header.Set("Content-Type", "application/json")
 

libs/apps/vite/bridge.go

@@ -133,7 +133,7 @@ func NewBridge(ctx context.Context, w *databricks.WorkspaceClient, appName strin
 }
 
 func (vb *Bridge) getAuthHeaders(wsURL string) (http.Header, error) {
-	req, err := http.NewRequestWithContext(vb.ctx, "GET", wsURL, nil)
+	req, err := http.NewRequestWithContext(vb.ctx, http.MethodGet, wsURL, nil)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create request: %w", err)
 	}

libs/auth/credentials_test.go

@@ -176,7 +176,7 @@ func TestCLICredentialsConfigure(t *testing.T) {
 			}
 
 			// Verify the credentials provider sets the correct Bearer token.
-			req, err := http.NewRequest("GET", tt.cfg.Host, nil)
+			req, err := http.NewRequest(http.MethodGet, tt.cfg.Host, nil)
 			if err != nil {
 				t.Fatalf("creating request: %v", err)
 			}

libs/testproxy/server.go

@@ -62,7 +62,7 @@ func New(t testutil.TestingT) *ProxyServer {
 func (s *ProxyServer) reqBody(r testserver.Request) any {
 	// The SDK expects the query parameters to be specified in the "request body"
 	// argument for GET, DELETE, and HEAD requests in the .Do method.
-	if r.Method == "GET" || r.Method == "DELETE" || r.Method == "HEAD" {
+	if r.Method == http.MethodGet || r.Method == http.MethodDelete || r.Method == http.MethodHead {
 		queryParams := make(map[string]any)
 		for k, v := range r.URL.Query() {
 			queryParams[k] = v[0]