[Central Beds] Change colour of tree asset

[MorayMySoc]

Switches tree asset to green when seen on the map https://mysocietysupport.freshdesk.com/a/tickets/4076

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[codecov[bot]]

Codecov Report

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

Project coverage is 82.79%. Comparing base (ce80472) to head (380dcae). Report is 4 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5046 +/- ## ========================================== + Coverage 82.65% 82.79% +0.13% ========================================== Files 396 396 Lines 30828 31314 +486 Branches 4890 4894 +4 ========================================== + Hits 25482 25925 +443 - Misses 3900 3942 +42 - Partials 1446 1447 +1 ```

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