Looks like psfrags interacts badly with\newgeometry, so we need to
use\geometry instead in the custom preamble to set the paper size.

In turn this means that\usepackage{geometry} needs to move to before
the custom preamble intoTexManager._get_preamble(), and thus we
can't pass the dvips option to it anymore, but fortunately dvips is
documented as the default driver anyways (section 5.6 ofgeometry
docs). Also, in order to keep everything under 79 characters wide,
change{72in,72in} to just72in (which is synonymous per section
4.3.3 ofgeometry docs).

Also insert some extra newlines in the generated tex file for ease of
debugging.

Closes#16898; sorry I don't have a test for now.

PR Summary

PR Checklist

• Has Pytest style unit tests
• Code isFlake 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way