Remove image max-size for centered images in PDF exports

[fdalcin]

Issue #850

This PR removes image adjustments on PDFs for centered aligned images (see).

How to test

1. Import an image, and insert as "large" into a chapter.
2. Set an alignment for center, left or right.
3. Export as a PDF
4. Left and right aligned images should have the sized adjusted. Centered images should remain untouched.

[codecov]

Codecov Report

Merging #851 (3261344) into dev (f1dd339) will not change coverage.
The diff coverage is n/a.

❗ Current head 3261344 differs from pull request most recent head a9c0280. Consider uploading reports for the commit a9c0280 to get more accurate results

@@           Coverage Diff           @@
##              dev     #851   +/-   ##
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  Coverage   48.27%   48.27%           
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  Files           4        4           
  Lines         464      464           
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  Hits          224      224           
  Misses        240      240           

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[SteelWagstaff]

LGTM

[SteelWagstaff]

Works as expected on integrations. Images which are center aligned or no alignment do not have a special max-width applied in exports. Images which are left or right aligned are set to max-width: 50% in export files.