[mlir][Linalg] Revisit heuristic ordering of tensor.insert_slice in comprehensive bufferize.

It was previously assumed that tensor.insert_slice should be bufferized first in a greedy fashion to avoid out-of-place bufferization of the large tensor. This heuristic does not hold upon further inspection.

This CL removes the special handling of such ops and adds a test that exhibits better behavior and appears in real use cases.

The only test adversely affected is an artificial test which results in a returned memref: this pattern is not allowed by comprehensive bufferization in real scenarios anyway and the offending test is deleted.

Differential Revision: https://reviews.llvm.org/D110072