Modify NsdServiceTest to conform to its new mechanism

Adapt NsdServiceTest to its new mechanism for starting/stopping daemons.
Also, add a new test for the new self-cleanup mechanism.

Bug: 181810560
Test: atest NsdServiceTest
Change-Id: I4c485a5d8fb4d6f52d82633a579bce4feb5c6375
1 file changed