Query editor connections aren't bound to the query tabs properly

Steps to reproduce:

• Open the query editor with 1 worksheet and 1 query tab.
• Create connections to two listeners or servers. e.g. Read-Write-Listener, Read-Only-Listener.
• Add a new query tab for the Read-Only-Listener connection
• Switch back to the Read-Write-Listener

The query editor failed to bind the existing connection because it only has 1 connection but there are now two query tabs. The query editor needs to handle this case.