Summary
Child ticket of WT-8663. 0 story points as the cost is already covered by the parent ticket.

In connection.h there are multiple occurrences where wt_thread_t variables have the same helper variables defined:
WT_CONDVAR xxx_cond;
WT_SESSION_IMPL xxx_session;
wt_thread_t xxx_tid;
bool xxx_tid_set;

and a large amount of code using these variables that is similar across all threads.

This ticket is to investigate if we can take these similar code patterns and capture it in subfunctions.