Remove French-only PDF fallback pages

[janriokrause]

Summary

complete-pdf and free-pdf-editor are now 301'd to www.firefox.com, so their routes and FR-only templates were dead code. Also drops the unused fr branch from firefox_features_pdf.

Follow-up cleanup for issue #16395, on top of PR #16867.

Follow-up

Six templates (nothing-personal, features/index, and the four compare/* pages) still link to the PDF editor via url('firefox.features.pdf-editor'), which is the only reason that route, view, and pdf-editor.html are kept around. If we hardcode those links straight to www.firefox.com, we could delete the route and template entirely, but it reaches into pages outside the PDF scope so it is a separate follow-up. Any suggestions?

Maybe <a href="{{ settings.FXC_BASE_URL }}/features/pdf-editor/?redirect_source=mozilla-org" ...> or something different?

Current approach is in line 194

bedrock/bedrock/firefox/templates/firefox/nothing-personal/index.html

Lines 189 to 195 in e755480

	<div class="c-feature-box" data-animation="pop-in">
	<h3 class="c-feature-box-title c-mono-title mzp-u-title-2xs">
	<img class="c-feature-box-image" src="{{ static('img/firefox/nothing-personal/feature-following.svg') }}" alt="">
	<span>Features with a following</span>
	</h3>
	<p><a href="{{ url('firefox.features.index') }}" target="_blank" data-link-text="Our actually-useful features">Our actually-useful features</a> are kind of a big deal. Fan favorites include <a href="{{ url('firefox.features.picture-in-picture') }}" target="_blank" data-link-text="popping out videos">popping out videos</a> and a <a href="{{ url('firefox.features.pdf-editor') }}" target="_blank" data-link-text="popping out videos">built-in PDF editor</a>.</p>
	</div>

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.88%. Comparing base (e755480) to head (ff07aaf).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17263      +/-   ##
==========================================
+ Coverage   82.84%   82.88%   +0.04%     
==========================================
  Files         178      178              
  Lines        9414     9409       -5     
==========================================
  Hits         7799     7799              
+ Misses       1615     1610       -5     

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[stevejalim]

R+

you could merge this as-is and do your follow-up separately, or bundle it all into here - I am easy either way.

In terms of the link to FXC, I think your in-markup solution <a href="{{ settings.FXC_BASE_URL }}/features/pdf-editor/?redirect_source=mozilla-org" ...> will do the job - it's obvious about what it's doing 👍

[janriokrause]

@stephaniehobson mentioned in Slack that pages like nothing-personal could also be removed. So there's no fix needed. Could you say a word about it, Stephanie? And what do you think, @stevejalim?