Remove Optimize method signature for BlockMatrix (#5834)
Remove Optimize method signature for BlockMatrix (#5834)

Unused and incorrect -- if this method were used, it would not optimize
any IRs in the DAG, which may contain relational or value IRs.
cseed/hail,hail-is/hail,danking/hail,danking/hail,cseed/hail,cseed/hail,cseed/hail,hail-is/hail,cseed/hail,hail-is/hail,cseed/hail,hail-is/hail,cseed/hail,cseed/hail,danking/hail,hail-is/hail,danking/hail,danking/hail,hail-is/hail,danking/hail,danking/hail,danking/hail,hail-is/hail,hail-is/hail