Stats refresh taking more than 2 hours to update

[ramyaragupathy]

Per reports from project managers, stats update for hashtag has not been happening for a while, resulting in stale data. To fix this we made some changes to the DB in January. This involves:

• Including a vacuum operation with each refresh cycle
• Remove the 2 hours timeout for each refresh

@dakotabenjamin has made the necessary changes to the script, which will be come through a separate PR. Dakota - can you also please check if the vaccum could be performed concurrently without creating any read/write lock?

cc @danbjoseph @bopercival-hot

[dakotabenjamin]

The command run from the housekeeping script is VACUUM (VERBOSE), which is a plain (i.e. not FULL) vacuum operation. Per docs that means it happens without obtaining an exclusive lock.

In addition, the changes that we have made are already live on the production resource, this PR will bring the changes back upstream.