Update release comment handler for mentions

[claudiaregio]

Enhance release comment handler to more users to mention since it was capping out at 50

[emaf]

Overall this is a nice cleanup — merging the two steps removes the GITHUB_ENV fragility and per_page: 100 is the right fix for the cap.

One minor thing: the PR removes the early-exit guard for when there are zero participants, but the prerelease message doesn't have a mentions check like the stable branch does. If all_users is empty, the message would be posted starting with a blank line:

// prerelease (current) - no guard
message = `${mentions}\n\nA fix for this issue is now available...`;

// stable - has a guard ✅
message = mentions.trim() !== ""
  ? `${mentions}\n\nThis issue has been fixed!...`
  : `This issue has been fixed!...`;

Worth adding the same guard to the prerelease branch for consistency:

message = mentions.trim() !== ""
  ? `${mentions}\n\nA fix for this issue is now available...`
  : `A fix for this issue is now available...`;