Remove undefined variable from c-ts-common.el

This variable came from code copied from c-indent-new-comment-line.
It's a parameter meant to be used by c-context-line-break, not a
global variable.

* lisp/progmodes/c-ts-common.el (c-ts-common-comment-indent-new-line):
Remove reference to undefined variable.  (Bug#74149)

lisp/progmodes/c-ts-common.el

@@ -336,7 +336,7 @@ and /* */ comments.  SOFT works the same as in
 	   (delete-horizontal-space)
 	   (if soft
 	       (insert-and-inherit ?\n)
-	     (newline (if allow-auto-fill nil 1))))))
+	     (newline 1)))))
     (cond
      ;; Line starts with //, or ///, or ////...
      ;; Or //! (used in rust).