Enable stubbing method for checking cross user permission in unit tests.

When running telecom unit tests on watch, we encountered exception when
checking cross user permissions. Add stubbing method so that we can
avoid these exceptions.

Bug: b/301148792
Test: atest TelecomTestCases:BasicCallTests
Change-Id: I2750a2846501e01056a386fd59b66a9e1c31527a
1 file changed