Fix IPA passkey feature detection

[ikerexxe]

Replace ipa help user | grep user-add-passkey with direct command test ipa user-add-passkey --help to avoid terminal environment issues when running in SSH sessions without proper TTY allocation.

[gemini-code-assist]

Code Review

This pull request updates the feature detection logic in sssd_test_framework/hosts/ipa.py by replacing a piped grep command with a direct help check for ipa user-add-passkey. This change simplifies the command and ensures both standard output and error are suppressed. I have no feedback to provide as there are no review comments.

[alexey-tikhonov]

There is a lot of other places where grep is used:

sssd_test_framework/hosts/ldap.py:60:            grep -r "passkey" /etc/dirsrv/ &> /dev/null && echo "passkey" || :
sssd_test_framework/hosts/client.py:57:            systemctl cat sssd.service | grep -q "If service configured to be run under" && echo "non-privileged" || :
sssd_test_framework/hosts/client.py:58:            strings /usr/lib64/sssd/libsss_ldap_common.so | grep ldap_use_ppolicy && echo "ldap_use_ppolicy" || :
sssd_test_framework/hosts/client.py:60:            MANWIDTH=10000 man sssd.conf | grep -q "id_provider = ldap or id_provider = proxy" && \
sssd_test_framework/hosts/samba.py:77:            timeout 60s bash -c 'until netstat -ltp 2> /dev/null | grep :ldap &> /dev/null; do :; done'
sssd_test_framework/hosts/samba.py:78:            timeout 60s bash -c 'until netstat -ltp 2> /dev/null | grep :kerberos &> /dev/null; do :; done'
sssd_test_framework/utils/automount.py:108:        mount | grep "{export.hostname}:{export.fullpath} on {path}"
sssd_test_framework/utils/authentication.py:498:                env | grep ^UMOCKDEV_ >> /usr/libexec/sssd/passkey_child

Aren't those affected by the same issue?