Support for changing or removing autolink

[janhoy]

Seems that currently you can only add autolink_jira keywords, not delete or modify. If a project no longer want to autolink a jira keyword they need to file an INFRA issue.

We should implement such that

• if the autolink_jira section is removed from .asf.yaml, all autolinks are removed
• If the autolink_jira section is modified, i.e. one entry removed, then we find what the "diff" is and issue such commands to github

[sebbASF]

If that cannot be implemented, it would be helpful to note the need to contact Infra in the documentation - maybe even say now that it is not yet possible.

[janhoy]

I put up a PR (kindly written by Claude Fable 5)