CI validation of Pull Requests is broken

[Enrico Olivelli <eo...@gmail.com>]

Hello,


GitHub validation stopped to work
styfle/cancel-workflow-action@0.6.0 is not allowed to be used in
apache/bookkeeper. Actions in this workflow must be: created by GitHub,
within a repository owned by apache or match the following: apache/*,
adoptopenjdk/*, gradle/wrapper-validation-action.

This is because recently Apache GitHub actions cannot use no more third
party actions, present in repositories that are not from trusted entities.

This is my hotfix
https://github.com/apache/bookkeeper/pull/2526

Basically it removes the untrusted action, that is only an optimization of
the process, as it cancels previous actions executions.
As that action is quite common, probably it is some kind of "common" action
that will be made available from ASF, please follow builds@apache.org in
order to see the discussion.

Please take a look to the patch
Enrico