Avoid shutting down of a passed executor

For the case where an executor is being provided we
should not shutdown the executor on-behalf of the
provider since they would likely expect that they
can still use the executor elsewhere. If the executor
is shutdown then further usage is not possible.

Change-Id: Ia83d8c2f1df06200e32e9b0c7340f32e74fd5d85
Merge "Avoid shutting down of a passed executor"