Revert "Frameworks: Move SharedPreferencesImpl to Future"

This reverts commit 70b600d4.

In preparation for a different fix. There are too many loopholes
with updates vs commits.

Bug: 67986472
Bug: 71533447
Test: m
Test: Device boots
Test: m cts && cts-tradefed run commandAndExit cts-dev --module CtsContentTestCases -c android.content.cts.SharedPreferencesTest
Change-Id: I872a81ae1a26e1f77aad2a52daf88e093a686ec6