patch 8.2.1128: the write message mentions characters, but it's bytes

Problem:    The write message mentions characters, but it's actually bytes.
Solution:   Change "C" to "B" and "characters" to "bytes".
diff --git a/src/testdir/test_netbeans.vim b/src/testdir/test_netbeans.vim
index 52c3782..8a35389 100644
--- a/src/testdir/test_netbeans.vim
+++ b/src/testdir/test_netbeans.vim
@@ -501,7 +501,7 @@
   let l = readfile('Xnetbeans')
   call assert_equal('send: 3:insertDone!78 T F', l[-1])
   sleep 1m
-  call assert_match('.*/Xfile4" 3L, 0C', v:statusmsg)
+  call assert_match('.*/Xfile4" 3L, 0B', v:statusmsg)
   let g:last += 3
 
   " saveDone test
@@ -511,7 +511,7 @@
   let l = readfile('Xnetbeans')
   call assert_equal('send: 3:saveDone!79', l[-1])
   sleep 1m
-  call assert_match('.*/Xfile4" 3L, 0C', v:statusmsg)
+  call assert_match('.*/Xfile4" 3L, 0B', v:statusmsg)
   let g:last += 3
 
   " unimplemented command test