Bug 1631839 - part 3: Remove "project.mobile" routes

[JohanLorenzo]

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.

After merge

• Milestone: Make sure issues finished by this pull request are added to the milestone of the version currently in development.

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 #12821 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master   #12821      +/-   ##
============================================
- Coverage     27.12%   27.09%   -0.03%     
  Complexity      955      955              
============================================
  Files           401      401              
  Lines         15979    15980       +1     
  Branches       2033     2033              
============================================
- Hits           4334     4330       -4     
- Misses        11318    11322       +4     
- Partials        327      328       +1     

Impacted Files	Coverage Δ	Complexity Δ
...mponents/searchengine/FenixSearchEngineProvider.kt	62.16% <0.00%> (-3.61%)	13.00% <0.00%> (ø%)
...ug/java/org/mozilla/fenix/DebugFenixApplication.kt	0.00% <0.00%> (ø)	0.00% <0.00%> (ø%)

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[JohanLorenzo]

@liuche May I get this patch cherry-picked to releases/79.0.0 and releases/79.1.0? I checked there's no conflicts, but I don't have enough rights to push there