fix(slack): Ensure notifications for same issue are seen

[ykamo001]

When the issue alert flow gets triggered for the same issue, we should ensure the notification gets seen in the main channel as well. Refactored some code a little to clean it up.

Resolves: #70135 (comment)

[cathteng]

do we have a test for this 😅

otherwise lgtm

[ykamo001]

do we have a test for this 😅

otherwise lgtm

Unfortunately we mock all slack api calls, so it won't test anything. In general though, it does not look like this class or method has any tests at all 😅

We have used this param for slack in another flow though, so we can be confident it does work

[ykamo001]

do we have a test for this 😅
otherwise lgtm

Unfortunately we mock all slack api calls, so it won't test anything. In general though, it does not look like this class or method has any tests at all 😅

We have used this param for slack in another flow though, so we can be confident it does work

for reference: https://api.slack.com/methods/chat.postMessage#arg_reply_broadcast

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 79.82%. Comparing base (df71fec) to head (101e473).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #70108      +/-   ##
==========================================
- Coverage   79.82%   79.82%   -0.01%     
==========================================
  Files        6504     6504              
  Lines      289377   289378       +1     
  Branches    49833    49833              
==========================================
- Hits       230989   230982       -7     
- Misses      57977    57985       +8     
  Partials      411      411              

Files	Coverage Δ
.../sentry/integrations/slack/actions/notification.py	80.32% <66.66%> (-0.67%)	⬇️

... and 7 files with indirect coverage changes