IpManager: fix test for default ProvisioningConfiguration

The test did not properly account for the stopAllIP() done in starting
state of the IpManager state machine, which could cause assertions to
fail when stopAllIP() is called again after stop().

Bug: 62988545
Test: runtest frameworks-net
Change-Id: I2c6eb76461a81c1d743bf448da36c58a99ce082d