repl: changes ctrl+u to delete from cursor to line start

Closes: #20145

PR-URL: #20686
Fixes: #20145
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/readline.js

@@ -800,10 +800,8 @@ Interface.prototype._ttyWrite = function(s, key) {
         }
         break;
 
-      case 'u': // delete the whole line
-        this.cursor = 0;
-        this.line = '';
-        this._refreshLine();
+      case 'u': // delete from current to start of line
+        this._deleteLineLeft();
         break;
 
       case 'k': // delete from current to end of line