[Dev] Use pull request's head remote when submitting crossbow jobs via the comment bot

[asfimport]

Reporter: Krisztian Szucs / @kszucs
Assignee: Krisztian Szucs / @kszucs

PRs and other links:

• GitHub Pull Request #9978

_{Note: This issue was originally created as ARROW-12327. Please see the migration documentation for further details.}

[asfimport]

Krisztian Szucs / @kszucs:
Issue resolved by pull request 9978
#9978