CLEANUP: channel: No longer notify the producer in co_skip()/co_htx_skip()

Thanks to the commit "BUG/MINOR: applet: Notify the other side if data were
consumed by an applet", it is no longer necessary to notify the producer when an
applet skips output data. Now, it is the default applet handler responsibility
to take care of that.
diff --git a/include/haproxy/channel.h b/include/haproxy/channel.h
index 65c294f..aa1996f 100644
--- a/include/haproxy/channel.h
+++ b/include/haproxy/channel.h
@@ -925,36 +925,26 @@
  * when data have been read directly from the buffer. It is illegal to call
  * this function with <len> causing a wrapping at the end of the buffer. It's
  * the caller's responsibility to ensure that <len> is never larger than
- * chn->o. Channel flags WRITE_PARTIAL and WROTE_DATA are set.
+ * chn->o.
  */
 static inline void co_skip(struct channel *chn, int len)
 {
 	b_del(&chn->buf, len);
 	chn->output -= len;
 	c_realign_if_empty(chn);
-
-	/* notify that some data was written to the SI from the buffer */
-	chn->flags |= CF_WRITE_PARTIAL | CF_WROTE_DATA;
-	chn_prod(chn)->flags &= ~SI_FL_RXBLK_ROOM; // si_rx_room_rdy()
 }
 
 /* HTX version of co_skip(). This function skips at most <len> bytes from the
  * output of the channel <chn>. Depending on how data are stored in <htx> less
- * than <len> bytes can be skipped. Channel flags WRITE_PARTIAL and WROTE_DATA
- * are set.
+ * than <len> bytes can be skipped..
  */
 static inline void co_htx_skip(struct channel *chn, struct htx *htx, int len)
 {
 	struct htx_ret htxret;
 
 	htxret = htx_drain(htx, len);
-	if (htxret.ret) {
+	if (htxret.ret)
 		chn->output -= htxret.ret;
-
-		/* notify that some data was written to the SI from the buffer */
-		chn->flags |= CF_WRITE_PARTIAL | CF_WROTE_DATA;
-		chn_prod(chn)->flags &= ~SI_FL_RXBLK_ROOM; // si_rx_room_rdy()
-	}
 }
 
 /* Tries to copy chunk <chunk> into the channel's buffer after length controls.