This change optimizes live queries by pushing the computation of query
targets to the creation time of the query, and efficiently caching the
targets in Redis. This results in a huge performance improvement at both
steady-state, and when running live queries.
- Live queries are stored using a bitfield in Redis, and takes
advantage of bitfield operations to be extremely efficient.
- Only run Redis live query test when REDIS_TEST is set in environment
- Ensure that live queries are only sent to hosts when there is a client
listening for results. Addresses an existing issue in Fleet along with
appropriate cleanup for the refactored live query backend.
