[mlir][ArmSME] Move tests out of `vector-ops-to-llvm.mlir` (#89905)

These tests basically were integration tests as unit tests, checking too
many passes at once to be useful, and brittle to any changes.

This patch moves (non-duplicated) tests to `vector-to-arm-sme.mlir`
(which only tests `-convert-vector-to-arm-sme`). The lowering after 
that e.g. `ArmSME -> SCF` and `ArmSME -> LLVM` already have their 
own set of tests covering these cases.