CI: Replace the container used in the nsenter tests (#368)

* Replace the container used in the nsenter tests.

* Improve connection tests.g

* Use quay.io/ansible/ansible-runner:devel instead.

tests/integration/targets/connection_nsenter/runme.sh

@@ -4,7 +4,7 @@ set -euo pipefail
 
 [[ -n "${DEBUG:-}" || -n "${ANSIBLE_DEBUG:-}" ]] && set -x
 
-readonly IMAGE="quay.io/ansible/toolset:latest"
+readonly IMAGE="quay.io/ansible/ansible-runner:devel"
 readonly PYTHON="$(command -v python3 python | head -n1)"
 
 # Determine collection root

tests/integration/targets/connection_posix/test.sh

@@ -5,7 +5,9 @@ set -eux
 # Connection tests for POSIX platforms use this script by linking to it from the appropriate 'connection_' target dir.
 # The name of the inventory group to test is extracted from the directory name following the 'connection_' prefix.
 
-group=$(python -c \
+PYTHON="$(command -v python3 python | head -n1)"
+
+group=$(${PYTHON} -c \
     "from os import path; print(path.basename(path.abspath(path.dirname('$0'))).replace('connection_', ''))")
 
 cd ../connection