Add pod annotation on PgBouncer

[herlambang]

Adding capability to define pod annotation for PgBouncer.

Ability to define pod annotation on PgBouncer pods.
Sample case: provide annotation for prometheus scraper that configured to look after pod annotation instead of service annotation.

^ Add meaningful description above

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[jedcunningham]

Overall looks good, just couple minor things to clean up.

[josh-fell]

@jedcunningham How does this compare/differ from #30168?

[potiuk]

@jedcunningham How does this compare/differ from #30168?

Except the name of the annotations they looks suspiciously the same :)

[herlambang]

Didn't realize it, probably I should close this instead, sorry