apply_remote test takes too long

[sithhell]

We are currently seeing that the apply_remote test takes up to almost 2 minutes. When looking at the test itself, it is rather simple and the plain test is actually finishing very quickly. The remaining time (up to 2 minutes) is spent in shutdown, mostly in the termination detection. This needs to be optimized.
To reproduce, run the apply_remote_test on two localities. Any number of threads per locality is fine, the behavior doesn't change. This might be related to #1251.

[sithhell]

Fixed with 17dd2eb