Mark the concrete SIMD/Scalar comparisons disfavored (#82686)
Adding the concrete versions (https://github.com/swiftlang/swift/pull/81892) introduced an ambiguity for concrete vec .<= .zero comparisons; previously the concrete SIMD .<= SIMD operation would win (because we didn't have a concrete overload for SIMD .<= SIMD.Scalar). We can restore the old behavior by marking these disfavored.
