test: use t.Context() instead of context.Background() (#1306)

The test context is cancelled when the test ends, so anything still holding it stops instead of leaking into the next test. Uses inside `t.Cleanup`, `defer` and `go func` blocks are left alone, as the context is already cancelled there.

Stacked on https://gitea.com/gitea/runner/pulls/1305.

Assisted-by: Codet
Co-authored-by: bircni <[email protected]>
Reviewed-on: https://gitea.com/gitea/runner/pulls/1306
Reviewed-by: bircni <[email protected]>

internal/pkg/envcheck/docker_test.go

@@ -11,7 +11,7 @@ import (
 )
 
 func TestCheckIfDockerRunningReturnsPingError(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(t.Context())
 	cancel()
 
 	err := CheckIfDockerRunning(ctx, "unix:///definitely/missing/docker.sock")