Allow configurable after_script timeouts

Description

Allow configurable after_script timeouts so that post script cleanup can be done here even when it takes longer than 5 minutes.

This can be nice for semantically breaking up when things happen but also if you want something to always run even if the script failed but it takes more than 5 minutes.

I'm currently just moving it into a script action because I don't really need it to fire on failure (waiting for an ECS deployment to finish draining previous tasks).

Proposal

The after_script timeout is currently hardcoded to 5 minutes. It would be nice to make this optionally configurable just like the main script actions are.

In the original issue raised about adding after_script it was noted that this was planned to be some arbitrary timeout with a later configuration option

Links to related issues and merge requests / references

https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/issues/102#note_11665572

Please paste a link of the related issues or/and merge requests