sql: introduce Transaction ID Cache

[cockroach-teamcity]

Exalate commented:

cockroachdb/cockroach#74115 --- Release note (sql change): Transaction ID to Transaction Fingerprint ID mapping is now stored in the new Transaction ID Cache, a FIFO unordered in-memory buffer. The size of the buffer is 64 MB by default and configurable via sql.contention.txn_id_cache.max_size cluster setting. Consequentially, two additioanl metrics are introduced: * sql.contention.txn_id_cache.size: tracks the current memory usage of transaction ID Cache * sql.contention.txn_id_cache.discarded_count: number of resolved transaction IDs that are dropped due to memory constraints.

Jira Issue: DOC-2473

Jira Issue: DOC-4260