feat(coderd/database/dbtestutil): set default database timezone to non-UTC in unit tests (#9672)

- Adds dbtestutil.WithTimezone(tz) to allow setting the timezone for a test database.
- Modifies our test database setup code to pick a consistently weird timezone for the database.
- Adds the facility randtz.Name() to pick a random timezone which is consistent across subtests (via sync.Once).
- Adds a linter rule to warn against setting the test database timezone to UTC.

coderd/workspaces_test.go

@@ -1514,8 +1514,13 @@ func TestWorkspaceFilterManual(t *testing.T) {
 
 	t.Run("LastUsed", func(t *testing.T) {
 		t.Parallel()
+
+		// nolint:gocritic // https://github.com/coder/coder/issues/9682
+		db, ps := dbtestutil.NewDB(t, dbtestutil.WithTimezone("UTC"))
 		client, _, api := coderdtest.NewWithAPI(t, &coderdtest.Options{
 			IncludeProvisionerDaemon: true,
+			Database:                 db,
+			Pubsub:                   ps,
 		})
 		user := coderdtest.CreateFirstUser(t, client)
 		authToken := uuid.NewString()