docs: Add docs for GLOBAL_ASYNC_QUERIES (SIP-39)

[robdiciuccio]

SUMMARY

Adds documentation for GLOBAL_ASYNC_QUERIES feature, including all configuration settings. See #11499 for related code.

ADDITIONAL INFORMATION

• Has associated issue: [SIP-39] Global Async Query Support #9190
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[codecov-io]

Codecov Report

Merging #12573 (f33f2bf) into master (deebd6f) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #12573   +/-   ##
=======================================
  Coverage   66.75%   66.75%           
=======================================
  Files        1015     1015           
  Lines       49633    49633           
  Branches     4839     4839           
=======================================
+ Hits        33133    33134    +1     
+ Misses      16377    16376    -1     
  Partials      123      123           

Flag	Coverage Δ
cypress	51.02% <ø> (+0.04%)	⬆️
javascript	60.74% <ø> (ø)
python	63.96% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...set-frontend/src/dashboard/util/getDropPosition.js	93.65% <0.00%> (+1.58%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update deebd6f...f33f2bf. Read the comment docs.

[junlincc]

we cut rc4 and kicked off the vote on Friday night. Async query docs update can go in the patch release, right? as it's not directly related to any urgent issues. given that we have Monday off, and announcing 1.0 on Thursday, we won't have enough time to the get this in. have to change label to v.1.0.1. 🙏

[villebro]

LGTM. If there are any Celery/Redis specific configs that have been found to work well it could also be nice to add those to the documentation (see e.g. #11499 (comment) )