Zooming on pages is currently disabled for reasons mentioned in rP953ab039acc0894e287304364920bc7cc4962cc0 from 2017.
This violates WCAG and is especially unhelpful on a mobile phone to see a larger version of an image file.
Thus allow zooming, crossing fingers that mobile platforms have reduced the unwanted side effects over the last seven years.

Closes T15945

Use Firefox on an Android phone in portrait orientation; Visit a Phorge task which has an image embedded; Click on the image comment; Pinch with fingers to zoom.