Fix comments around static constructor memory

[jkotas]

Delete unnecessary MemoryBarrier

Contributes to #81151

[VSadov]

We also access the cctorMethodAddress in stubs like:

runtime/src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/DependencyAnalysis/Target_ARM64/ARM64ReadyToRunHelperNode.cs

Line 36 in 1cc0186

encoder.EmitLDR(encoder.TargetRegister.Arg2, encoder.TargetRegister.Arg3);

For completeness of the fix those should also be volatile reads.

Ideally that would be in C#, so less trouble with hand encoded assembly. Not sure what scenario uses those (Reflection?) and whether it would be noticeable if the stubs do not try to short-circuit and just call here unconditionally.

[VSadov]

LGTM!

[VSadov]

I think the asm stubs could be dealt with separately.