build: streamline ci

[qued]

Updated CI to shave time off in some conditions with no real downside.

• When the base cache already exists, we don't download it during setup, and we skip all other steps as well.
• During ingest setup, we check if the ingest cache exists before downloading the base cache, and if the ingest cache already exists, we skip everything else.
• check-deps doesn't have to wait on setup or download a cache, as the dependencies aren't needed, only pip.

CI version	Setup (on hit)	Ingest Setup (on hit)	Check deps (on hit)
Old	2:06-2:31	3:07-3:31	3:19-6:26
New	0:08-0:09	0:07-0:09	2:05-2:23

Testing

• Results of cache hits (best case scenario) can be seen here.
• Results of old cache hits can be seen here.

[cragwolfe]

tricky