Merge the changes about the tests repeated setResolverConfiguration

===
Refactor the test code that checks the cleartext DNS stats

The test code for stats check is slightly stricter than before since
now it checks almost every field rathern few of them.

Bug: 150678049
Test: resolv_integration_test passed
Change-Id: I86294a9d3a6050ccf8057b34eaa3463e00742850
===
Add tests to cover repeated setResolverConfiguration

Two tests are added to protect the resolver when it continually
receives the same setup requests.

When the resolver receives repeated and same setup:
[1] Do not clear the cache.
[2] Do not clear the stats (the stats for cleartext DNS servers
    got from GetResolverInfo()).
[3] Do not start a new re-evaluation process for the private DNS
    servers if they have been marked as in_progress.
[4] Need not to re-validate the private DNS servers if they have
    been validated.

Another test is added to protect the implementation of aosp/1108695.

Fix: 150678049
Test: resolv_integration_test passed
Change-Id: I7a866e7e305c0fb703ccb9546d1c70ce77e2d3c7
===

Bug: 150678049
Merged-In: I86294a9d3a6050ccf8057b34eaa3463e00742850
Merged-In: I7a866e7e305c0fb703ccb9546d1c70ce77e2d3c7
Change-Id: I69f449c578799a9437e38743557b8c1bc52d4046
(cherry picked from commit 3ccd410b)