upstream tests: Removal of 'warn: no' from shell plugins

The parameter 'warn' from ansible.builtin.shell was deprecated in
ansible-core version 2.11 and removed in version 2.14.

This patch removes the usage of this parameter from ansible-freeipa
tests, and adds 'deprecated-command-syntax' to the skip list of
ansible-lint configuration to cope with the change in the linter.