Remove unused ACCESS_NETWORK_STATE permission

Since TetheringCoverageTests would include NetworkStackTestsLib and
tethering has unit test case that tests ACCESS_NETWORK_STATE permission.
That test would assume the test package do not define
ACCESS_NETWORK_STATE permission and use adopt/drop shell permission to
simulate whether caller hold ACCESS_NETWORK_STATE permission.

Since NetworkStackTests do not use ACCESS_NETWORK_STATE permission,
remove it to avoid to be inherited by its user(TetheringCoverageTests).

Bug: 154869719
Test: TetheringCoverageTests, NetworkStackTests, NetworkStackNextTests
Merged-In: Ic45add1eaed0bd30788544b1b5bfd0f39a85a364
Change-Id: Ic45add1eaed0bd30788544b1b5bfd0f39a85a364