Restore errormessage CI coverage (#54355)

* Initial plan

* Restore errormessage CI coverage

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Avoid rebuilding errormessage linter in CGO

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Log missing push base for errormessage lint

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Use push commit range for errormessage lint

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Clarify errormessage diff ranges

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Tighten errormessage diff comment

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Use direct push diff for errormessage lint

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>