Stabilize TestDetect by serializing Maven-dependent subtests

[Copilot]

TestDetect/Full and TestDetect/ExcludePatterns were running concurrently and both invoking real mvn against the shared local .m2 cache, causing intermittent artifact download temp-file races. This change removes that intra-test concurrency while preserving package-level parallelism.

• Change: serialize TestDetect subtests

  • Removed subtest-level t.Parallel() from TestDetect in internal/appdetect/appdetect_test.go.
  • TestDetect itself remains parallelized relative to other tests/packages.

• Impact

  • Prevents concurrent Maven processes from contending on shared .m2 state during cold-cache dependency resolution.
  • Scope is limited to test code in internal/appdetect; no changes to Maven implementation or resolver flags.

for _, tt := range tests {
	t.Run(tt.name, func(t *testing.T) {
		// t.Parallel() removed to avoid concurrent mvn access to shared ~/.m2
		projects, err := Detect(t.Context(), dir, tt.options...)
		require.NoError(t, err)
		// ...
	})
}