[Fixes #12441] GS layers metadata update

[giohappy]

Checklist

Reviewing is a process done by project maintainers, mostly on a volunteer basis. We try to keep the overhead as small as possible and appreciate if you help us to do so by completing the following items. Feel free to ask in a comment if you have troubles with any of them.

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• [ ] There is a ticket in https://github.com/GeoNode/geonode/issues describing the issue/improvement/feature (a notable exemption is, changes not visible to end-users)
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[codecov[bot]]

Codecov Report

Attention: Patch coverage is 39.28571% with 17 lines in your changes missing coverage. Please review.

Project coverage is 64.15%. Comparing base (fffa2d5) to head (f625f63).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #12442 +/- ## ======================================= Coverage 64.15% 64.15% ======================================= Files 888 888 Lines 53468 53465 -3 Branches 6599 6596 -3 ======================================= + Hits 34300 34302 +2 Misses 17654 17654 + Partials 1514 1509 -5 ```