(docker) trim down docker image (300M -> 12M) / binary built without symbol and size optimization, and source code not copied over

tools/trim_repo_for_docker.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# Used to clean up some non essential folders to make the ws container
+
+rm -rf build
+rm -rf third_party/zlib
+rm -rf third_party/mbedtls