Working towards clean-up comments /**/ in cs (dotnet/coreclr#20609)

Working towards clean-up comments /**/ in cs (dotnet/coreclr#20609)

* Working towards cleaning comments /**/

Cleaningup /**/ style comments - Following https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/xmldoc/recommended-tags-for-documentation-comments

dotnet/coreclr#20330

* Updating tags

-Updating some <sumary> to <remarks>
-Adding missing tags

* Fixing PR comments

-Comment does not belong to the public description

* Hiding comment from public description.

* Update //***** to the prevalent // style.

Commit migrated from https://github.com/dotnet/coreclr/commit/3ed48433718f870cdf258ac10bcd6eead6beb2b9