[Surrey] Adds google tag

[MorayMySoc]

https://github.com/mysociety/societyworks/issues/4307

Some discussion on things I'm not clear on as this basically replicates Merton: https://mysociety.slack.com/archives/C06M1A7QXPZ/p1716476520990489 https://mysociety.slack.com/archives/C01TK8P1K8T/p1716538448735839?thread_ts=1716481887.898449&cid=C01TK8P1K8T

[skip changelog]

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.56%. Comparing base (8dd40a3) to head (b73b14c).

:exclamation: Current head b73b14c differs from pull request most recent head d8181aa

Please upload reports for the commit d8181aa to get more accurate results.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## surrey-cobrand-config-extra #4974 +/- ## ============================================================ Coverage 82.56% 82.56% ============================================================ Files 392 392 Lines 30511 30511 Branches 4815 4815 ============================================================ Hits 25190 25190 + Misses 3885 3884 -1 - Partials 1436 1437 +1 ```

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