Remove subscription_stability_test.go and improve test variable naming

Deleted `subscription_stability_test.go` to clean up unused or redundant code. Updated naming in test files for improved readability, replacing `tag` with `tg` for consistency. Also updated the `github.com/klauspost/compress` dependency to v1.18.2.

pkg/policy/new_fields_test.go

@@ -896,7 +896,7 @@ func TestFollowsWhitelistAdminsWithWriteAllow(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			// Generate if needed
 			if tt.signer.Pub() == nil {
-				tt.signer.Generate()
+				_ = tt.signer.Generate()
 			}
 
 			ev := createTestEventForNewFields(t, tt.signer, "test", 1)