Links to Jira issue comments are not converted to GitHub issue comments

[mocobeta]

We convert Jira cross-issue links (LUCENE-XXXX) to GitHub issue links (#NN).
However, links to Jira comments are not converted into links to GitHub comments since we don't have a mapping from Jira comment id to GitHub comment id.

Original Jira:
https://issues.apache.org/jira/browse/LUCENE-9414?focusedCommentId=17142414&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-17142414

Migrated issue:
https://github.com/mocobeta/forks-migration-test-3/issues/9378#issuecomment-1211440645

Creating a mapping for comments is not a trivial task (GitHub import API does not return the comment ids), though, in theory, it should be possible by iterating all comments in Jira and GitHub.
Links to comments are relatively rare, I think we can leave this unresolved.