Improve how parcels are recycled on AssisStructure custom parcelization.

1.Make sure the temporary data parcel is always recycled.
2.Recycle the parcel attribute after data is fully fetched on go().

Bug: 68604253

Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases
Test: cts-tradefed run commandAndExit cts-dev -m CtsAssistTestCases

Change-Id: Ifb2f1d088260384f7523ca6d02631ec56535ac0a