Clean up as much as possible in a single pass for the EphemeralRunner reconciler

[nikola-jokic]

In addition to cleaning up as many resources as possible in a single pass on the ephemeral runner reconciler, an additional check has been added to check if the container has a hook configured.

The check goes through the runner's environment variables and looks for ACTIONS_RUNNER_CONTAINER_HOOKS.
Previously, the controller would always check if there were leftover resources linked to the runner. This check is not necessary when the container hook is not configured.

Also, it is important to point out that in most cases, there will be no resources linked to the runner, unless the runner is forcefully terminated without having a chance to call the hook to clean them up. Nevertheless, the only way to configure the container hook for the runner is to pass the ACTIONS_RUNNER_CONTAINER_HOOKS environment variable to the container. Unless the environment variable is baked into the custom-built runner image, the check will work as expected.