Refactor meta to commit catalogs only after first barrier

[kwannoel]

1. IF committed after first barrier, it means that the actors have been initialized.
2. Things like alter rate limit can then take effect for an in progress stream job.
3. Also it will fix the inconsistent behaviour of show jobs for background ddl. When barrier latency is high, background ddl still returns immediately, but is not visible in show jobs, until the first barrier is collected.