async search

search currently happens in every node by default, and it's full text (regex even) search. this is very costly, I knew when adding it but it was just too convenient and useful to have it :)
today on 2021-08-14 I'll try to fix this by making search be an async action: search only triggers when users reach the bottom of the page or request searching explicitly.
- this will have the nice side effect of making the agora cheap by default when servicing bot requests, which probably won't run the javascript that is needed to retrieve search.
initial testing with ab (I know, old school)
- ab -n 100 -c 10 https://1.anagora.org/index
  - ~10 seconds overall, 50% ~0.6 seconds, 99% ~2 seconds
- on localhost (dev instance) the 99% goes up to 50-60 seconds, there are clear hangs.
- before and after cache
testing after disabling full text search:
- on localhost (dev instance) the 99% goes down to 3-6s (!). as expected, but nice to see.
this didn't end up being enough to fix significant spikes of latency in high percentiles, so added uwsgi caching also.
- see before and after cache