Change SetLink signature to return the link's ID, not update

[dmathieu]

Part of #14016

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.67%. Comparing base (c854264) to head (2e2616a).
⚠️ Report is 26 commits behind head on main.

Files with missing lines	Patch %	Lines
pdata/pprofile/links.go	60.00%	2 Missing ⚠️

❌ Your patch status has failed because the patch coverage (60.00%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #14031   +/-   ##
=======================================
  Coverage   91.67%   91.67%           
=======================================
  Files         654      654           
  Lines       42619    42607   -12     
=======================================
- Hits        39069    39061    -8     
+ Misses       2738     2735    -3     
+ Partials      812      811    -1     

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[dmathieu]

Note that there is no contrib change required here, since this method isn't used there.