[scd] inline cleanup of implicit subscription into CRDB call when removing OIR

[Shastick]

This is the first part of #1059:

It quite literally moves the Go logic into SQL, by means of nested queries and conditional DELETE statements.

(The PR sits on top of #1057)

Test plan:

this PR survives a run of every current uss_qualifier configuration when run locally and also passes the prober (both on CI and locally)

[mickmis]

I wanted to start the review of this PR but:

1. Is it appropriate to start relying more on CRDB given the current pending decisions? cc @BenjaminPelletier
2. Is it reviewable in current state? It looks out of date from [scd] properly cleanup implicit sub on oir update #1057 @Shastick

[BenjaminPelletier]

I do think we want to continue to maintain our current products until we have a positive new direction. We probably don't want to focus on optimizations targeted specifically for CRDB (though it's probably still valuable to complete outstanding work even if it did target CRDB specifically), but it seems like this improvement would be mostly applicable for most alternative SQL options.

[Shastick]

Is it reviewable in current state? It looks out of date from #1057 @Shastick

This PR does not strictly need to be up to date with #1057 as it is going to replace the Go logic from #1057 with subqueries: I would definitely wait for the other to be merged before merging this one, but the approach using subqueries can already be discussed and reviewed.

[Shastick]

Replaced with #1107