RUBY-2454 Fix aws configurations test failures (#2141)

Co-authored-by: Oleg Pudeyev <oleg@bsdpower.com>

Author: p-mongo

.evergreen/functions-server.sh

@@ -56,12 +56,12 @@ prepare_server_from_url() {
 }
 
 install_mlaunch_virtualenv() {
-  #export PATH=/opt/python/3.7/bin:$PATH
-  python -V || true
-  python3 -V || true
-  #pip3 install --user virtualenv
+  python2 -V || true
+  # Current virtualenv fails with
+  # https://github.com/pypa/virtualenv/issues/1630
+  python -m pip install 'virtualenv<20' --user
   venvpath="$MONGO_ORCHESTRATION_HOME"/venv
-  virtualenv $venvpath
+  python2 -m virtualenv -p python2 $venvpath
   . $venvpath/bin/activate
   pip install 'mtools-legacy[mlaunch]'
 }

.evergreen/run-tests.sh

@@ -25,7 +25,7 @@ setup_ruby
 
 prepare_server $arch
 
-install_mlaunch_pip
+install_mlaunch_virtualenv
 
 # Launching mongod under $MONGO_ORCHESTRATION_HOME
 # makes its log available through log collecting machinery