[clang] [llvm] [mlir] [polly] Remove unneeded cl::Optional and cl::ZeroOrMore. NFC (PR #225628)

[Alexis Engelke via llvm-commits]

https://github.com/aengelke commented:

There should be never a reason to specify cl::Optional as it is the default, right? cl::Optional removal LGTM.

ZeroOrMore is not completely trivial, as it might, albeit unlikely, change semantics if all given values for the option are inspected. I haven't reviewed the uses of all affected options and would suggest splitting this off (possibly separating Bolt as well) to make it more reviewable.

https://github.com/llvm/llvm-project/pull/225628