patch 9.0.2132: Duplicate Netbeans Error Message

patch 9.0.2132: Duplicate Netbeans Error Message

Problem:  Duplicate Netbeans Error Message
Solution: Remove duplicate message

We have 2 error Messages used for the Netbeans interface:

- EXTERN char e_invalid_buffer_identifier_in_close[]
  INIT(= N_("E648: Invalid buffer identifier in close"));
- EXTERN char e_invalid_buffer_identifier_in_close_2[]
  INIT(= N_("E649: Invalid buffer identifier in close"));

Since the error message is exactly the same, get rid of the  second
message.

closes: #13584

Signed-off-by: Christian Brabandt <cb@256bit.org>