One of the problems of QueryAnalyzers is that their state
is evaluated each time. This is problematic for various reasons
as we need to re-evaluate feature flags, or other dynamic conditions.

This makes QueryAnalyzers behavior sticky. The enabled flag is checked
exactly once for each request/worker/spec. If it resolves to true,
the query analyzer will be enabled for the whole execution of a job.

This makes also QueryAnalyzer to hold a context that is set/reset
on boundaries of job execution.