improvement: limit app connection concurrent syncs

backend/src/keystore/keystore.ts

@@ -38,6 +38,7 @@ export const KeyStorePrefixes = {
   SyncSecretIntegrationLastRunTimestamp: (projectId: string, environmentSlug: string, secretPath: string) =>
     `sync-integration-last-run-${projectId}-${environmentSlug}-${secretPath}` as const,
   SecretSyncLock: (syncId: string) => `secret-sync-mutex-${syncId}` as const,
+  AppConnectionConcurrentJobs: (connectionId: string) => `app-connection-concurrency-${connectionId}` as const,
   SecretRotationLock: (rotationId: string) => `secret-rotation-v2-mutex-${rotationId}` as const,
   SecretScanningLock: (dataSourceId: string, resourceExternalId: string) =>
     `secret-scanning-v2-mutex-${dataSourceId}-${resourceExternalId}` as const,