Delete simple unused vars2 (dotnet/coreclr#23491)

Delete simple unused vars2 (dotnet/coreclr#23491)

* Clean `valuenum.cpp`.

* Clean `emitarm64.cpp`.

* Clean `lsraarm64.cpp`.

* Clean `lsraarmarch.cpp`.

* Clean `lowerarmarch.cpp`.

* Clean `lower.cpp`.

* Clean `ssabuilder.cpp`.

* Clean `simd.cpp`.

* Clear `simdcodegenxarch.cpp`.

* Clean `lowerxarch.cpp`.

* Clean `scopeinfo.cpp`.

Commit migrated from https://github.com/dotnet/coreclr/commit/ecf92d0664acc8a36ee7ae69efefca5bb5a7dee5