[Backport #14609 to 5.0.x] Limit embed endpoints to GET only (#14609)

[sijandh35]

(cherry picked from commit 1e60dcf)

Backport #14609

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.

For all pull requests:

• Confirm you have read the contribution guidelines
• You have sent a Contribution Licence Agreement (CLA) as necessary (not required for small changes, e.g., fixing typos in the documentation)
• Make sure the first PR targets the master branch, eventual backports will be managed later. This can be ignored if the PR is fixing an issue that only happens in a specific branch, but not in newer ones.

The following are required only for core and extension modules (they are welcomed, but not required, for contrib modules):

• 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)
• The issue connected to the PR must have Labels and Milestone assigned
• PR for bug fixes and small new features are presented as a single commit
• PR title must be in the form "[Fixes #<issue_number>] Title of the PR"
• New unit tests have been added covering the changes, unless there is an explanation on why the tests are not necessary/implemented

Submitting the PR does not require you to check all items, but by the time it gets merged, they should be either satisfied or inapplicable.

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 30 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (5.0.x@de528c5). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff            @@
##             5.0.x   #14612   +/-   ##
========================================
  Coverage         ?   26.89%           
========================================
  Files            ?      945           
  Lines            ?    57383           
  Branches         ?     7809           
========================================
  Hits             ?    15432           
  Misses           ?    41361           
  Partials         ?      590           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.