Duplicate delete the user_project_metadata.

When assignment backend is sql,duplicate delete the user_project_metadata
filter with project_id when delete project.No need to do this.

This patch fix the bug.

Change-Id: Ic90798737b3f7f4418ce6ffbf1d9c945449798ca
Closes-Bug: #1248037
Merge "Duplicate delete the user_project_metadata."