[SDFAB-1197] First stab to update ONOS to py3

Update has been performed only on the scripts and the
executables strictly necessary for the following use cases:

- Build (including Intellij)
- Tests (including Intellij)
- Docker build (including dev and yourkit)
- Upload snapshot (including local)
- Release

Finally, fix the ability to run ONOS using onos-local targets,
stc and docker stc (aka up4 stc env). Last but not least, updated
the azul image to a newer one which exports also the PYTHONENCODING

Change-Id: Ie96f3a9c76dbba83b1fc3896a372f1045d3d7ccc
diff --git a/.bazelrc b/.bazelrc
index 2b9ed65..5faf22a 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -12,7 +12,7 @@
 build --tool_java_language_version=11
 build --tool_java_runtime_version=remotejdk_11
 
-build --host_force_python=PY2
+build --host_force_python=PY3
 
 build --nouse_ijars
 build --experimental_strict_action_env