[Dev] Remove github user names from merge commit message

[asfimport]

We currently use the top post comment body of a github PR as the body of the commit message. It is not uncommon to tag someone when opening a PR, but retaining those github usernames in the commit message is annoying as that can generate additional notifications for the people that were tagged.

It should be straightforward to remove the github user names from the message body (for example, just remove the @, so it doesn't work anymore as user name link)

Reporter: Joris Van den Bossche / @jorisvandenbossche
Watchers: Rok Mihevc / @rok

Related issues:

• [Dev] Merge script could warn if username pings would be present in commit message (is duplicated by)

_{Note: This issue was originally created as ARROW-18096. Please see the migration documentation for further details.}

[asfimport]

Rok Mihevc / @rok:
Similar to ARROW-17025

[asfimport]

Joris Van den Bossche / @jorisvandenbossche:
Indeed, thanks!