[MLIR] Clean up checks for alloc-like ops in analysis

Clean up checks for alloc-like ops in analysis. Use the analysis
utility to properly check for the desired kind of effects. The previous
locality utility worked for all practical purposes but wasn't sound and
was locally duplicate code. Instead, use mlir::hasSingleEffect.

Reviewed By: rriddle

Differential Revision: https://reviews.llvm.org/D129439