[mono] block debugger attach after managed ApplyUpdate is called  #55228

Block two scenarios:

1. managed ApplyUpdate is called with debugger attached
2. debugger tries to attach after managed ApplyUpdate is called.

The issue is that if updates and debugger state are out of sync, we don't have a mechanism to play the debugger up to the modified state so attaching would see outdated breakpoints, locals, etc. Revisit in future releases.

The only supported scenarios are:

• all updates come in through the debugger protocol
• all updates come from ApplyUpdate and the debugger never attaches