Remove FTP exemption from port blocking

Chrome no longer supports FTP.

Bug: 333943
Change-Id: I4c52c7fda6fc6adbda3a0612b24dcf524c54e4b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3139191
Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Eric Lawrence [MSFT] <ericlaw@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#917853}

net/base/port_util.cc

@@ -181,11 +181,6 @@ bool IsPortAllowedForScheme(int port, base::StringPiece url_scheme) {
   if (g_explicitly_allowed_ports.Get().count(port) > 0)
     return true;
 
-  // FTP requests are permitted to use port 21.
-  if (base::LowerCaseEqualsASCII(url_scheme, url::kFtpScheme) && port == 21) {
-    return true;
-  }
-
   // Finally check against the generic list of restricted ports for all
   // schemes.
   for (int restricted_port : kRestrictedPorts) {