chore(enterprise/coderd): remove dbmem from tests (#18797)

Related to https://github.com/coder/coder/issues/15109.

enterprise/coderd/enidpsync/organizations_test.go

@@ -53,10 +53,6 @@ type OrganizationSyncTestCase struct {
 func TestOrganizationSync(t *testing.T) {
 	t.Parallel()
 
-	if dbtestutil.WillUsePostgres() {
-		t.Skip("Skipping test because it populates a lot of db entries, which is slow on postgres")
-	}
-
 	requireUserOrgs := func(t *testing.T, db database.Store, user database.User, expected []uuid.UUID) {
 		t.Helper()