*: migrate DDLs run with internal executor to CollectionFactory.TxnWithExecutor()

[ZhouXing19]

The previous design of the internal executor itself is erroneous when running a DDL in a not nil transaction, for it creates its own set of descriptor collection and schema change job records. The internal executor depends on the descriptor collection to see catalog writes in the current transaction. Without coupling that internal executor to the collection, the queries will use a leased descriptor and not see the write.

The new CollectionFactory.TxnWithExecutor() will solve this problem by always passing the same txn-related meta info to the child conn executor in the internal executor, if it is run within the same txn.

Epic CRDB-14492
Jira issue: CRDB-19251

[blathers-crl]

Hi @ZhouXing19, please add branch-* labels to identify which branch(es) this release-blocker affects.

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