Separate servicestests/utils

The test utility classes under com.android.server.testutils are moved
to servicestests/utils directory in order to easily be shared between
FrameworksServiceTests and upcomming WmTests.

Test: tradefed.sh run commandAndExit FrameworksServicesTests \
    --include-annotation android.platform.test.annotations.Presubmit \
    --exclude-annotation androidx.test.filters.FlakyTest
Bug: 113800711
Merged-In: I39c623a286df1067fffadc25c8a49c12cc05c82c
Change-Id: I71cd7b417641b5e969bef6f3076020bfc1dfffa7
(cherry picked from commit 77439ba9)