release-23.1.0: catalog: utilize scans for a large number of descriptors

[blathers-crl]

Backport 1/1 commits from #101937 on behalf of @fqazi.

/cc @cockroachdb/release

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Previously, the catalog descriptor would fetch descriptors via point lookups using Get when scanning large batches of descriptors. This was further extended to also look up ZoneConfigs and comments in a similar way. Recently, we we started seeing regression on the Django test suite involving the pg_catalog tables, which tend to do read large number of descriptors, likely linked to extra overhead linked to both comments and zone configs in 23.1. To address this, this patch ill now start using scans for runs of descriptor IDs for batch scans which reduces the overall cost of fetching a large number of descriptors hiding this cost.

Fixes: #100871

Release note: None

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Release justification: low risk and address a major regression on the Django test suite

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[cockroach-teamcity]

This change is 

[fqazi]

@rimadeodhar @chengxiong-ruan TFTR