fix: Fix AppLayoutToolbar breadcrumbs SSR glitch (take three)

[TrevorBurnham]

Description

Previously: #3856, #4065

Embarrassingly, that second PR was missing one of the two changes needed (as seen on the original branch), so it was insufficient to fix the glitch. This PR brings over that other change and adds test coverage for it.

Fixes #3848 cc @pan-kot

How has this been tested?

I've confirmed this fix locally by cherry-picking this SSR dev server commit and running it.

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[TrevorBurnham]

FYI you can now validate these change by cherry-picking it onto this PR branch: #4127 Then visit http://localhost:8080/app-layout-toolbar/with-content-layout. You'll see that the sidebar toggle and content are still missing during the SSR render, but the breadcrumbs are correctly positioned.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.14%. Comparing base (4dcdb39) to head (13679db).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4123   +/-   ##
=======================================
  Coverage   97.14%   97.14%           
=======================================
  Files         869      869           
  Lines       25473    25473           
  Branches     9208     9209    +1     
=======================================
  Hits        24745    24745           
+ Misses        722      681   -41     
- Partials        6       47   +41     

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