Warnings depend on order of constant prop and compiler-generated code detection

[sbomer]

See tests added in dotnet/linker#2928 and dotnet/linker#2931.

When constant propagation removes calls to a local function, the compiler-generated state may or may not detect the user method which owns the local function. It depends on whether it gets a chance to inspect the user method before constant propagation.

dotnet/linker#2931 shows a case where this can produce different warning behavior when RUC on the user method may or may not suppress a warning from the local function.