Use TestableLooper.RunWithLooper instead of manually setting it up

This may help with intermittent flakiness of looper in
testMultiSimConfigChanged. It's hard to verify this precisely, but at
least this change will do some minor cleanup around TestableLooper.

Bug: 365800992
Test: atest --rerun-until-failure 10 com.android.phone.CarrierConfigLoaderTest
Flag: TEST_ONLY
Change-Id: Ia1ade347d4580d253cac24e6f4c2591ad3c307c4
1 file changed