fix: debounce activity updates to handle rapid websocket updates

[bdraco]

• ensure the first poll of activity after a pubnub/websocket message is 1s later since there is a delay in the api updating
• ensure we cancel any pending polls on refresh
• ensure we cancel any pending polls on new pubnub/websocket message
• ensure we don't poll too quickly when we get a new pubnub/websocket message.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.71429% with 11 lines in your changes missing coverage. Please review.

Project coverage is 72.48%. Comparing base (78cf869) to head (8947a9f). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
yalexs/manager/activity.py	84.72%	6 Missing and 5 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #182 +/- ## =========================================== + Coverage 62.42% 72.48% +10.05% =========================================== Files 31 31 Lines 2249 2293 +44 Branches 388 396 +8 =========================================== + Hits 1404 1662 +258 + Misses 794 568 -226 - Partials 51 63 +12 ```

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