Replace `termination_policy` and `termination_idle_time` with `idle_duration: int|str|off`

[peterschmidt85]

I suggest that we drop termination_policy but rename termination_idle_time to idle_duration.
termination_idle_time is an important fieled but currently too long to be convenient to use. Also, I suggest that we use duration everywhere instead of somewhere time and somewhere duration.

[r4victor]

Looks good overall. Some notes:

1. We're going to introduce new retry policies in Improve retry policy #1200 so retry_duration alone is not sufficient. Let's do not touch retry_policy in this issue.
2. Regarding creation_policy, we don't have creation_policy: create. The addition of new policy should be discussed outside of renaming issue. Also, it's unclear what reuse: false|true|auto means. reuse: true may be misleading since it doesn't simply allows reuse but forces it. creation_policy: reuse|reuse-or-create is more clear. I'm against renaming this particular field as suggested.

[r4victor]

retry_policy renamed in #1200

[peterschmidt85]

This issue is stale because it has been open for 30 days with no activity.

[peterschmidt85]

This issue was closed because it has been inactive for 14 days since being marked as stale. Please reopen the issue if it is still relevant.

[peterschmidt85]

We still need to rename termination_idle_time: int|str -> idle_duration: int|str|off

[github-actions]

This issue is stale because it has been open for 30 days with no activity.

[github-actions]

This issue is stale because it has been open for 30 days with no activity.