log,server: avoid global variables to log/trace server IDs

[cockroach-teamcity]

Exalate commented:

cockroachdb/cockroach#73306 --- Release note (cli change): The server identifiers (cluster ID, node ID, tenant ID, instance ID) are not any more duplicated at the start of every new log file (during log file rotations). They are now only logged when known during server start-up. (The copy of the identifiers is still included in per-event envelopes for the various json output logging formats.)

Jira Issue: DOC-2169

[exalate-issue-sync]

Ryan Kuo (taroface) commented:
Cancelled as this doesn’t require docs.