fetch schema through dedicated api endpoint
What does this MR do and why?
this merge requests make it so the graphql adaptor fetches schema through the dedicated api endpoint instead of through the recently barricaded classical graphql endpoint. I assume the change in the graphql endpoint happened due to CVE-2025-8099 (though it isn't yet public enough that i know for sure). It is required to use graphql with the gitlab-triage gem on up-to-date gitlab, but I don't know if this fix is actually functional on out-of-date gitlab.