For #9946: Update FennecBeta branding

[sblatz]

This is now ready to land!

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-io]

Codecov Report

Merging #10066 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master   #10066   +/-   ##
=========================================
  Coverage     19.26%   19.26%           
  Complexity      532      532           
=========================================
  Files           340      340           
  Lines         13790    13790           
  Branches       1847     1847           
=========================================
  Hits           2657     2657           
  Misses        10895    10895           
  Partials        238      238           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5d51c4f...8755d5a. Read the comment docs.

[kglazko]

Correct icons are in this PR