Revert "[MLIR] Fuse locations of merged constants (#74670)"

This reverts commit 87e2e890.
and its follow-ups 0d1490f0 (#75218)
and 6fe3cd54 (#75312).

We observed significant OOM/timeout issues due to #74670 to quite a few
services including google-research/swirl-lm. The follow-up #75218 and
 #75312 do not address the issue. Perhaps this is worth more
investigation.