Vertify the exact interactions with mocking object

There are more than 1 interaction inside verifySetupPlatformVpn.
The original code does not actually wait for the target
interaction with Executor.schedule(). The interact may happen
after reset the mocking object. This will leave a unexpected
interaction in the follow up verification and cause a flaky
test.

This test was fine in the initial patch, but becomes failed
after the time unit used in Executor.schedule() was changed
to milliseconds for data stall recovery. Both interactions
for data stall ones and non-data stall ones will be captured
together after that.

Bug: 289961869
Test: atest VpnTest --rerun-until-failure 20
Change-Id: If24e323b366bb15b81fe9fa554fa7ccc852ba6f1