Call loadPageData() as needed in Title::moveToInternal.

* This avoids use of a slave for loading the page ID to do
  the updates using $newpage. That bug prevented page moves
  by using the old 0 ID and throwing an exception.

Bug: 46397
Change-Id: Iea3259dce6840e3f2959d98a20177acd60433b64
Merge "Call loadPageData() as needed in Title::moveToInternal."