[FixaMinGata] Add various updates

[jonkri]

Some minor FixaMinGata-related changes. The empty public_update.html file is intentional (we are currently not using this section of the inspect form).

• [ ] Has the code POD documentation been added or updated?
• [ ] Whether this PR should include changes to any public documentation, or the FAQ;
• [x] All cobrand-specific commits start their commit message with the cobrand in square brackets;
• [ ] Is new functionality tested? CodeCov will warn you about the diff coverage, but won’t complain about e.g. new files;
• [ ] Will cobrand-specific changes require additional work to ensure consistent behaviour on www.fixmystreet.com?
• [ ] Are the changes tested for accessibility?
• [ ] Have you updated the changelog? If this is not necessary, put square brackets around this: [skip changelog]

Related to #4235.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 69.18%. Comparing base (ce80472) to head (aedbdd2).

Files	Patch %	Lines
perllib/FixMyStreet/Cobrand/FixaMinGata.pm	0.00%	1 Missing :warning:

:exclamation: There is a different number of reports uploaded between BASE (ce80472) and HEAD (aedbdd2). Click for more details.

HEAD has 13 uploads less than BASE

| Flag | BASE (ce80472) | HEAD (aedbdd2) | |------|------|------| ||15|2|

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5050 +/- ## =========================================== - Coverage 82.65% 69.18% -13.47% =========================================== Files 396 340 -56 Lines 30828 24586 -6242 Branches 4890 4649 -241 =========================================== - Hits 25482 17011 -8471 - Misses 3900 6224 +2324 + Partials 1446 1351 -95 ```

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