[gdbplugin] fixed removing unresolved breakpoints
When a the DAP server was unable to resolve a requested break-point (eg. uninterruptable line or at unknown source file), the break-point tables were not properly updated and the application could crash due to accessing unbound indices.
Proposed test:
- Start a session with golang delve.
- Set a break-point in a line with a closing bracket (no break-point is set because is invalid for the server).
- Try to seat the same break-point again (this should remove the break-point as requested by the user).
- List break-points with the command 'bl'
- Kate should not crash.