[BUG] Don't remove builtin OAuth2 applications

- When the database consistency is being run it would check for any
OAuth2 applications that don't have an existing user. However there are
few special OAuth2 applications that don't have an user set, because
they are global applications.
- This was not taken into account by the database consistency checker
and were removed if the database consistency check was being run with
autofix enabled.
- Take into account to ignore these global OAuth2 applications when
running the database consistency check.
- Add unit tests.
- Ref: https://codeberg.org/Codeberg/Community/issues/1530

services/doctor/dbconsistency.go

@@ -8,6 +8,7 @@ import (
 
 	actions_model "code.gitea.io/gitea/models/actions"
 	activities_model "code.gitea.io/gitea/models/activities"
+	auth_model "code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/models/db"
 	issues_model "code.gitea.io/gitea/models/issues"
 	"code.gitea.io/gitea/models/migrations"
@@ -164,6 +165,12 @@ func checkDBConsistency(ctx context.Context, logger log.Logger, autofix bool) er
 			Fixer:        repo_model.DeleteOrphanedTopics,
 			FixedMessage: "Removed",
 		},
+		{
+			Name:         "Orphaned OAuth2Application without existing User",
+			Counter:      auth_model.CountOrphanedOAuth2Applications,
+			Fixer:        auth_model.DeleteOrphanedOAuth2Applications,
+			FixedMessage: "Removed",
+		},
 	}
 
 	// TODO: function to recalc all counters
@@ -208,9 +215,6 @@ func checkDBConsistency(ctx context.Context, logger log.Logger, autofix bool) er
 		// find OAuth2Grant without existing user
 		genericOrphanCheck("Orphaned OAuth2Grant without existing User",
 			"oauth2_grant", "user", "oauth2_grant.user_id=`user`.id"),
-		// find OAuth2Application without existing user
-		genericOrphanCheck("Orphaned OAuth2Application without existing User",
-			"oauth2_application", "user", "oauth2_application.uid=`user`.id"),
 		// find OAuth2AuthorizationCode without existing OAuth2Grant
 		genericOrphanCheck("Orphaned OAuth2AuthorizationCode without existing OAuth2Grant",
 			"oauth2_authorization_code", "oauth2_grant", "oauth2_authorization_code.grant_id=oauth2_grant.id"),