Adds expirations for remote callbacks

Right now there is no timeout/expiration in the remote service. In cases
that the implementer of Rotation Resolver Service doesn't call back
and the pending callback blocks the following requests, we should
add an expiration of the pending callback in the remote service.

Bug: 186674250
Test: Manually tested the feature

Change-Id: I82f08155243e2205a2c95ae39c71c3118e9249ec