[Bexley WW] Simplify in-cab logs code to use USRN logs only

[nephila-nacrea]

We are pretty certain that UPRN logs are always a subset of USRN logs, so I have simplified the code so we only fetch USRN logs.

[skip changelog]

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 72.72727% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 82.60%. Comparing base (8cefb7e) to head (f2fc6f4).

:exclamation: Current head f2fc6f4 differs from pull request most recent head c3ec368

Please upload reports for the commit c3ec368 to get more accurate results.

Files	Patch %	Lines
perllib/FixMyStreet/Cobrand/Bexley/Waste.pm	72.72%	0 Missing and 3 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #4979 +/- ## ======================================= Coverage 82.59% 82.60% ======================================= Files 393 393 Lines 30756 30752 -4 Branches 4877 4877 ======================================= - Hits 25404 25402 -2 + Misses 3898 3896 -2 Partials 1454 1454 ```

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