utils/run-tests.sh: Install Ansible collections on virtual environment

When runing tests using 'utils/run-tests.sh' from inside an existing
Python virtual environment the Ansible collections are not installed due
to the order of execution of the script. On a machine that does not have
the 'containers.*' collection the test fails as there is no container
connector available.

This patch moves the section that installs Ansible collections to run
after the virtual environment is configured, and then install the
collections (usually, only 'containers.podman'), allowing the tests to
be executed.