[mlir][linalg] Remove the `test-linalg-to-vector-patterns` option (#142116)
This patch removes the `test-linalg-to-vector-patterns` option from the
`-test-linalg-transform-patterns=` test flag. It was only used in one
test, where a more specialized transform dialect op can be used instead:
* `transform.apply_patterns.linalg.pad_vectorization`
While we could preserve `test-linalg-to-vector-patterns`, it's better to
rely on finer-grained transformations — this way, we know exactly what
is being run and tested. Now that its only use has been removed, it
feels natural to delete `test-linalg-to-vector-patterns`.