Reconfigure docker builders to be more modular.

And other various cleanups to the configuration.

llvm-svn: 363722
diff --git a/libcxx/utils/docker/scripts/docker_start_buildbots.sh b/libcxx/utils/docker/scripts/docker_start_buildbots.sh
index 0531d6f..f47ddcd 100755
--- a/libcxx/utils/docker/scripts/docker_start_buildbots.sh
+++ b/libcxx/utils/docker/scripts/docker_start_buildbots.sh
@@ -1,12 +1,8 @@
 #!/usr/bin/env bash
 set -x
 
-if [[ "$1" == "--new" ]]; then
-  shift
-fi
-
 # Update the libc++ sources in the image in order to use the most recent version of
 # run_buildbots.sh
 cd /libcxx
 git pull
-/libcxx/utils/docker/scripts/run_buildbot_new.sh "$@"
+/libcxx/utils/docker/scripts/run_buildbot.sh "$@"