Issue #19846: Make sure default browser notification only happens once

[rocketsroger]

Pull Request checklist

• Tests: This PR includes thorough tests or an explanation of why it does not
• Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features. In addition, it includes a screenshot of a successful accessibility scan to ensure no new defects are added to the product.

To download an APK when reviewing a PR:

1. click on Show All Checks,
2. click Details next to "Taskcluster (pull_request)" after it appears and then finishes with a green checkmark,
3. click on the "Fenix - assemble" task, then click "Run Artifacts".
4. the APK links should be on the left side of the screen, named for each CPU architecture

[codecov-commenter]

Codecov Report

Merging #20373 (8c2976b) into master (317cbe9) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master   #20373      +/-   ##
============================================
- Coverage     36.07%   36.07%   -0.01%     
  Complexity     1564     1564              
============================================
  Files           538      538              
  Lines         20994    20994              
  Branches       3140     3140              
============================================
- Hits           7574     7573       -1     
- Misses        12573    12574       +1     
  Partials        847      847              

Impacted Files	Coverage Δ
...fenix/home/intent/DefaultBrowserIntentProcessor.kt	100.00% <ø> (ø)
...nix/onboarding/DefaultBrowserNotificationWorker.kt	1.92% <0.00%> (-0.04%)	⬇️

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[rocketsroger]

@Mergifyio backport releases_v91.0.0

[mergify]

Command backport releases_v91.0.0: success

Backports have been created

• #20383 Issue #19846: Make sure default browser notification only happens once (backport #20373) has been created for branch releases_v91.0.0