Move 'Block Phishing / Malware' option to the bottom

[luixxiul]

Closes #10813

Test Plan:

1. Open about:preferences#shields

cf: on the compact bravery panel

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Test Plan:

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[codecov-io]

Codecov Report

Merging #10816 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master   #10816   +/-   ##
=======================================
  Coverage   54.17%   54.17%           
=======================================
  Files         247      247           
  Lines       21548    21548           
  Branches     3338     3338           
=======================================
  Hits        11673    11673           
  Misses       9875     9875

Flag	Coverage Δ
#unittest	54.17% <0%> (ø)	⬆️

Impacted Files	Coverage Δ
js/about/preferences.js	42.32% <0%> (ø)	⬆️

[NejcZdovc]

++