[Echo] Better handling of downtime

[dracos]

(And a random issue I saw in the error log from BANES)

The excluded actions match what Apache currently lets through in the httpd.conf.

It also adds 2 hour warning of the downtime, which I thought could be useful!

[skip changelog]

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 80.76923% with 5 lines in your changes missing coverage. Please review.

Project coverage is 82.65%. Comparing base (41725ae) to head (44ecbfb). Report is 2 commits behind head on master.

Files	Patch %	Lines
perllib/FixMyStreet/Cobrand/HighwaysEngland.pm	0.00%	0 Missing and 2 partials :warning:
perllib/FixMyStreet/Cobrand/BathNES.pm	0.00%	1 Missing :warning:
perllib/FixMyStreet/Cobrand/Bexley.pm	0.00%	0 Missing and 1 partial :warning:
perllib/FixMyStreet/Roles/Cobrand/Echo.pm	95.23%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5075 +/- ## ========================================== - Coverage 82.65% 82.65% -0.01% ========================================== Files 403 403 Lines 31376 31398 +22 Branches 4973 4982 +9 ========================================== + Hits 25935 25951 +16 - Misses 3967 3969 +2 - Partials 1474 1478 +4 ```

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