[hma] Bad redirects on dev page

[sbruens]

The dev handlers (e.g. /dev/factory_reset) redirect to /dev/ which doesn't exist. It makes it seem like the action failed, when it's just the redirect that is bad. Example here:

ThreatExchange/hasher-matcher-actioner/src/OpenMediaMatch/blueprints/development.py

Line 104 in d4d343c

return redirect("./")

I think it can be done with redirect(url_for(ui.bp.home))? Let me give it a try and send a PR.

[Dcallies]

Might be a breakage from when I moved this out of /ui/ where this redirect made sense. I think your fix looks right.