Any JAR extension uninstall/upgrade on root namespace is blocked a very long time on myxwiki.org

It seems XWIKI-14494 added a blocking reload of all schedulers from all wikis when upgrading a JAR on root namespace.

On an instance like myxwiki.org, it means blocking forever since there are a lot of wikis.

There are two problems:

• the reload itself is a lot slower than it should: it actually changes and store the status of the job in the document, twice (to disable and then enable it), instead of just reloading it
• I really don't think we need to block the job while doing this, so it would make more sense to do this reload asynchronously