Prevent caching of board if isBoardLinkedToUser has changed

[jacbn]

Prevents the server returning the same board without the mutation applied if isBoardLinkedToUser has changed.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.27%. Comparing base (03b9dbb) to head (1ec6d76).

Files with missing lines	Patch %	Lines
...a/uk/ac/cam/cl/dtg/isaac/api/GameboardsFacade.java	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #801      +/-   ##
==========================================
- Coverage   40.28%   40.27%   -0.01%     
==========================================
  Files         547      547              
  Lines       23814    23817       +3     
  Branches     2898     2898              
==========================================
  Hits         9593     9593              
- Misses      13320    13323       +3     
  Partials      901      901              

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