Fix 'Modifying dpm.setSecureSetting call for install_non_market_apps'

The previous change was reverted as it broke work profile provisioning.
Clearing binder calling identity before calling into settings provider
should fix the issue.

Test: runtest managed-provisioning
Test: runtest -x services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java
Test: Manually tested that work profile is inflated with expected values
of install_non_market_apps

Bug: 33947615
Bug: 35590590

Change-Id: I3c31a73fef0c25c0e682e18f637272adad39b28d