release-22.1: sql: fix auto-retries for upgraded transactions

[blathers-crl]

Backport 1/1 commits from #84389 on behalf of @rafiss.

/cc @cockroachdb/release

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This is implemented by adding more state to the conn executor state
machine. Now, it tracks if the open transaction was upgraded from an
implicit to an explicit txn. If so, when doing an auto retry, the
transaction is marked as an implicit again, so that the statements in
the transaction can upgrade it to explicit.

No release note is needed for v22.2, but we should use the following
note when backporting to v22.1.

Placeholder note (bug fix): Fixed a bug where some statements in a batch
would not get executed if the following conditions were met:

• A batch of statements is sent in a single string.
• A BEGIN statement appears in the middle of the batch.
• The enable_implicit_transaction_for_batch_statements session variable
  is set to true. (This defaults to false in v22.1.x)

This bug was introduced in v22.1.2. (#82681)

Release note: None

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Release justification: bug fix

[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