Delete code examples for obsolete members

### Describe the issue or suggestion

Similar to #11345, but this issue is to find obsolete *members* and delete any code examples in *those members only*.

Rubric is delete code examples for members if the member is:

- Obsolete since .NET Framework 4 or earlier
- Obsolete in .NET and deprecated in .NET Fx (e.g. CAS)
- Obsolete in .NET and not editor browsable in .NET Fx