[mlir][ArmSME][test] Prepare tests for tile allocation changes (#91358)

This patch:

 1. Removes some duplicate test cases
 2. Removes unnecessary uses of `-convert-arm-sme-to-llvm`
 3. Ensures tile values have uses via `test.some_use()`

1 and 2 will make these tests easier to update. 3 will be needed as
ArmSME operations will be pure.