remove deprecated --remote-buffer

--remote-buffer is deprecated since 1.2.

there is --upload-buffer for the same purpose.

src/borg/archiver.py

@@ -2833,7 +2833,6 @@ class Archiver:
     def preprocess_args(self, args):
         deprecations = [
             # ('--old', '--new' or None, 'Warning: "--old" has been deprecated. Use "--new" instead.'),
-            ('--remote-buffer', None, 'Warning: "--remote-buffer" has been deprecated. Use --upload-buffer instead.'),
         ]
         for i, arg in enumerate(args[:]):
             for old_name, new_name, warning in deprecations:
@@ -3037,8 +3036,6 @@ class Archiver:
                               help='use PATH as borg executable on the remote (default: "borg")')
             add_common_option('--upload-ratelimit', metavar='RATE', dest='upload_ratelimit', type=int,
                               help='set network upload rate limit in kiByte/s (default: 0=unlimited)')
-            add_common_option('--remote-buffer', metavar='UPLOAD_BUFFER', dest='upload_buffer', type=int,
-                              help='deprecated, use ``--upload-buffer`` instead')
             add_common_option('--upload-buffer', metavar='UPLOAD_BUFFER', dest='upload_buffer', type=int,
                               help='set network upload buffer size in MiB. (default: 0=no buffer)')
             add_common_option('--consider-part-files', dest='consider_part_files', action='store_true',