Run genjsonschema in CI

[dmathieu]

#6347 is updating the generated JSON schema, as it has changed with upgrades of go-jsonschema.
We update the binary semi automatically with dependabot. However, this means there could be unseen regressions or changes like this that we miss.

This runs the schema generation on CI, before checking for a clean repository, so we can keep the generated code up to date with the binary version.

This should fail until #6347 and #6349 are merged.

[evan-bradley]

Thanks! Wasn't sure where to add this when updating the types, but this is the obvious next step to make sure they don't go out-of-date.

[pellared]

CC @codeboten

[dmathieu]

@open-telemetry/go-approvers this needs a second review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.9%. Comparing base (c873ddc) to head (bbf3451).
Report is 13 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #6353   +/-   ##
=====================================
  Coverage   66.9%   66.9%           
=====================================
  Files        193     193           
  Lines      15652   15647    -5     
=====================================
+ Hits       10479   10481    +2     
+ Misses      4882    4876    -6     
+ Partials     291     290    -1     

see 2 files with indirect coverage changes