macsec: T5447: fix error message syntax - there is no tx and rx key, only key (backport #3685)

[mergify]

Change Summary

Remove the TX and RX portion from the key error message as the CLI only offers key.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5447

Related PR(s)

• T5447: Initial support for MACsec static keys #2156

Component(s) name

Proposed changes

How to test

Smoketest result

[email protected]:~$ /usr/libexec/vyos/tests/smoke/cli/test_interfaces_macsec.py
test_add_multiple_ip_addresses (__main__.MACsecInterfaceTest.test_add_multiple_ip_addresses) ... ok
test_add_single_ip_address (__main__.MACsecInterfaceTest.test_add_single_ip_address) ... ok
test_dhcp_client_options (__main__.MACsecInterfaceTest.test_dhcp_client_options) ... ok
test_dhcp_disable_interface (__main__.MACsecInterfaceTest.test_dhcp_disable_interface) ... ok
test_dhcp_vrf (__main__.MACsecInterfaceTest.test_dhcp_vrf) ... ok
test_dhcpv6_client_options (__main__.MACsecInterfaceTest.test_dhcpv6_client_options) ... ok
test_dhcpv6_vrf (__main__.MACsecInterfaceTest.test_dhcpv6_vrf) ... ok
test_dhcpv6pd_auto_sla_id (__main__.MACsecInterfaceTest.test_dhcpv6pd_auto_sla_id) ... ok
test_dhcpv6pd_manual_sla_id (__main__.MACsecInterfaceTest.test_dhcpv6pd_manual_sla_id) ... ok
test_interface_description (__main__.MACsecInterfaceTest.test_interface_description) ... ok
test_interface_disable (__main__.MACsecInterfaceTest.test_interface_disable) ... ok
test_interface_ip_options (__main__.MACsecInterfaceTest.test_interface_ip_options) ... ok
test_interface_ipv6_options (__main__.MACsecInterfaceTest.test_interface_ipv6_options) ... ok
test_interface_mtu (__main__.MACsecInterfaceTest.test_interface_mtu) ... ok
test_ipv6_link_local_address (__main__.MACsecInterfaceTest.test_ipv6_link_local_address) ... ok
test_macsec_encryption (__main__.MACsecInterfaceTest.test_macsec_encryption) ... ok
test_macsec_gcm_aes_128 (__main__.MACsecInterfaceTest.test_macsec_gcm_aes_128) ... ok
test_macsec_gcm_aes_256 (__main__.MACsecInterfaceTest.test_macsec_gcm_aes_256) ... ok
test_macsec_source_interface (__main__.MACsecInterfaceTest.test_macsec_source_interface) ... ok
test_macsec_static_keys (__main__.MACsecInterfaceTest.test_macsec_static_keys) ... ok
test_mtu_1200_no_ipv6_interface (__main__.MACsecInterfaceTest.test_mtu_1200_no_ipv6_interface) ... ok
test_span_mirror (__main__.MACsecInterfaceTest.test_span_mirror) ... skipped 'not supported'
test_vif_8021q_interfaces (__main__.MACsecInterfaceTest.test_vif_8021q_interfaces) ... skipped 'not supported'
test_vif_8021q_lower_up_down (__main__.MACsecInterfaceTest.test_vif_8021q_lower_up_down) ... skipped 'not supported'
test_vif_8021q_mtu_limits (__main__.MACsecInterfaceTest.test_vif_8021q_mtu_limits) ... skipped 'not supported'
test_vif_8021q_qos_change (__main__.MACsecInterfaceTest.test_vif_8021q_qos_change) ... skipped 'not supported'
test_vif_s_8021ad_vlan_interfaces (__main__.MACsecInterfaceTest.test_vif_s_8021ad_vlan_interfaces) ... skipped 'not supported'
test_vif_s_protocol_change (__main__.MACsecInterfaceTest.test_vif_s_protocol_change) ... skipped 'not supported'

----------------------------------------------------------------------
Ran 28 tests in 154.662s

OK (skipped=7)

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

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This is an automatic backport of pull request #3685 done by [Mergify](https://mergify.com).