TelephonyProvider: Impressive performance improvement for Mms delete

1. Drop the trigger used to update word and threads when delete part
2. Drop the tirgger used to update threads when delete pdu
3. Use code to do the trigger's job, to avoid unnecessary operation
when delete a lot of mms.

CRs-Fixed: 620436

Change-Id: I5dd32eb66123953848989a18abd099c905b4d3d8