Disabling the restore option on the vttablet fails to setup metadata table

[ameetkotian]

Overview of the Issue

If -restore_from_backup is disabled, vttablet does not setup the _vt.local_metadata. _vt.local_metadata is used, among others, by tools like orchestrator to get shard information and failover logic.

Reproduction Steps

Steps to reproduce this issue, example:

1. Start a new tablet process without -restore_from_backup option.
2. Check the _vt database is empty:

 SELECT *  FROM _vt.local_metadata ;

The issue is populateMetadataTables is called only part of mysqlctl.Restore.

[derekperkins]

related to #3753

[derekperkins]

duplicate of #4006, but as this issue is better documented, I'll close the other issue.

cc @lokanadhamm