Added virtualenv to ruby and php73 docker for psm (#28263)

templates/tools/dockerfile/test/php73_zts_stretch_x64/Dockerfile.template

@@ -35,5 +35,8 @@
   <%include file="../../run_tests_python_deps.include"/>
   <%include file="../../php_common_deps.include"/>
   <%include file="../../run_tests_addons.include"/>
+
+  RUN python3 -m pip install virtualenv==16.7.9
+
   # Define the default command.
   CMD ["bash"]

templates/tools/dockerfile/test/ruby_buster_x64/Dockerfile.template

@@ -21,5 +21,8 @@
   <%include file="../../ruby_deps.include"/>
   <%include file="../../cmake.include"/>
   <%include file="../../run_tests_addons.include"/>
+
+  RUN python3 -m pip install virtualenv==16.7.9
+
   # Define the default command.
   CMD ["bash"]

tools/dockerfile/test/php73_zts_stretch_x64/Dockerfile

@@ -62,5 +62,8 @@ RUN mv composer.phar /usr/local/bin/composer
 
 RUN mkdir /var/local/jenkins
 
+
+RUN python3 -m pip install virtualenv==16.7.9
+
 # Define the default command.
 CMD ["bash"]

tools/dockerfile/test/ruby_buster_x64/Dockerfile

@@ -106,5 +106,8 @@ RUN apt-get update && apt-get install -y cmake && apt-get clean
 
 RUN mkdir /var/local/jenkins
 
+
+RUN python3 -m pip install virtualenv==16.7.9
+
 # Define the default command.
 CMD ["bash"]