parse userId from authority in opp in the same way as ContentProvider

Ensures that userId determination is consistent with ContentProvider

Bug: 395647005
Bug: 395643490
Flag: EXEMPT fix for vulnerability
Test: m com.google.android.bt
Test: atest BluetoothJavaUnitTests:com.android.bluetooth.opp.BluetoothOppSendFileInfoTest
Ignore-AOSP-First: fix for undisclosed vulnerability
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:bb8a03783901dc92738fdd9af6f3ca88feda4bcf)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:230fa5b83f10c34983cbf7637faef6c060b8ef25)
Merged-In: I7b6affec5dada7c9f0319fbdb35a6e977e51990f
Change-Id: I7b6affec5dada7c9f0319fbdb35a6e977e51990f