Docker: Clean up jruby temp files on restart

[orgads]

If the container is restarted multiple times, each restart generates ~8MB of jar files in /tmp/jruby-1.

Relates to #11051 (fixes it only for docker env).

[logstashmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[cla-checker-service[bot]]

💚 CLA has been signed

[orgads]

I signed the CLA.

[mergify[bot]]

This pull request does not have a backport label. Could you fix it @orgads? 🙏 To fixup this pull request, you need to add the backport labels for the needed branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• backport-8.x is the label to automatically backport to the 8.x branch.

[mergify[bot]]

backport-8.x has been added to help with the transition to the new branch 8.x. If you don't need it please use backport-skip label.

[orgads]

Rebased