[MLIR][SPIRVToLLVM] Indentation and style fix in tests

This is a first patch that sweeps over tests to fix
indentation (tabs to spaces). It also adds label checks and
removes redundant matching of `%{{.*}} = `.

The following tests have been fixed:
- arithmetic-ops-to-llvm
- bitwise-ops-to-llvm
- cast-ops-to-llvm
- comparison-ops-to-llvm
- logical-ops-to-llvm (renamed to match the rest)

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D85181