🔧 chore: fix sentry app notification action for bug found in dry run

[iamrajjoshi]

i found a bug in the dry run script where i don't migrate sentry apps which have the label key. This fixes that by passing it as None during migration.

In the long run, I think we should be updating the typing on the frontend so we don't it as optional, rather str | None, but until we get to that reality, I basically parse out the None inside the NOA so when we invoke the sentry app action, we omit the label if it doesn't exist.

[codecov]

Codecov Report

Attention: Patch coverage is 94.28571% with 2 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...gine/migration_helpers/test_migrate_rule_action.py	87.50%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #86261       +/-   ##
===========================================
+ Coverage   46.68%   87.89%   +41.20%     
===========================================
  Files        9697     9714       +17     
  Lines      550003   550978      +975     
  Branches    21446    21446               
===========================================
+ Hits       256766   484264   +227498     
+ Misses     292857    66334   -226523     
  Partials      380      380