IsReadOnlyAttribute is emitted even if coming from non-runtime reference

[vzarytovskii]

          Ok, it seems is is a separate bug, since System.Collections.Immutable inludes its own `IsReadOnlyAttribute`:

And we are checking it only by namespace, we decide to emit it but not generate attribute.

I will revert generating it altogether, until proper fix is in place (with codegen).

Originally posted by @vzarytovskii in #14276 (comment)

[SamuelBerger]

@vzarytovskii Will this be in the patch release of 2023-02-14 (even when it is not back ported to 17.5 #14704)?