disable htmx's history support, ensure caching takes htmx into account

[longhotsummer]

this fixes related issues:

1. htmx was using its own caching engine to refresh the full page contents when we provided hx-push-url in a response (eg. the work listing page). this caused our scripts to run twice, since htmx stores the full in the cache and re-loads it, without calling the server.
2. turning htmx history off with hx-history="false" means that it won't try to store anything in the cache, instead doing an AJAX request.
3. BUT, our server code thinks that's a partial page load, and so doesn't return a full response. So we turn off ajax htmx history off too.
4. finally, ensure we vary caches on the hx-request and hx-target attributes.

closes #2359

[longhotsummer]

See https://htmx.org/docs/#history for some details.

[github-actions]

Test Results

579 tests  ±0   579 ✅ ±0   4m 27s ⏱️ -1s
 60 suites ±0     0 💤 ±0 
 60 files   ±0     0 ❌ ±0 

Results for commit 42ec739. ± Comparison against base commit cb9a05a.

♻️ This comment has been updated with latest results.