fix(alerting): Use reflection to set invalid providers to nil instead of re-validating on every alert trigger/resolve

[TwiN]

Summary

Instead of re-validating the corresponding alerting provider of an alert every time said alert is triggered/resolved, use reflection to set the alerting configuration's provider field to nil

Checklist

• Tested and/or added tests to validate that the changes work as intended, if applicable.
• Added the documentation in README.md, if applicable.

[codecov-commenter]

Codecov Report

Base: 82.04% // Head: 82.04% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (bba7ad6) compared to base (9acace7).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #386   +/-   ##
=======================================
  Coverage   82.04%   82.04%           
=======================================
  Files          54       54           
  Lines        4065     4066    +1     
=======================================
+ Hits         3335     3336    +1     
  Misses        574      574           
  Partials      156      156           

Impacted Files	Coverage Δ
config/config.go	73.11% <100.00%> (+0.14%)	⬆️
watchdog/alerting.go	89.83% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.