Removing Chromoting Chrome app from official build rule

The Chrome app has been deprecated and replaced by a website.  I am now
cleaning up references to it throughout Chromium with the eventual goal
of removing the code.

Change-Id: I1e43659c82c79bb3a25b907496ee406b250e8e9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1926538Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Joe Downing <joedow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718795}

BUILD.gn

@@ -864,7 +864,6 @@ if (is_win) {
       "//components/zucchini",
       "//courgette",
       "//courgette:copy_courgette_binaries",
-      "//remoting/webapp",
       "//tools/metrics:metrics_metadata",
     ]