Fixing vtorc naming convention - database

[GuptaManan100]

Description

Cleanup references to master and slave in vt/orchestrator in the database that it uses

Related Issue(s)

• Task: Cleanup references to master and slave in vt/orchestrator #7110

Checklist

• Should this PR be backported?
• Tests were added or are not required
• Documentation was added or is not required

[shlomi-noach]

Overall good, and this seems correct. However, it looks like we're now also making a distinction between primary and source (e.g. you've defined source_host and source_port).

This means we need to be careful what we call "primary" (the top, wirteable server) and what we call "source" (the immediate parent in the topology). In light of that, there's various other variables that need to be renamed "primary"->"source".

This is at your discretion, because it goes a bit sideways to the original intention of this PR; I'm mentioning this because you seem to have made the distinction in some places, so we may as well make it all the way through.

[GuptaManan100]

Made all the requested changes @shlomi-noach

All requested changes have been made

[deepthi]

I have one suggestion:
seconds_behind_source -> replication_lag_seconds.
The rest LGTM