system k8s-certificate-list commands fails when Opaque type secret data is None

[ayyappa]

Brief Description
-----------------
When any of the k8s Opaque type secret data is None, the "system k8s-certificate-list" command fails

Severity
--------
Major.

Steps to Reproduce
------------------
1)Have opaque type secret with no data on the system
2)Run "system k8s-certificate-list"

Expected Behavior
------------------
"system k8s-certificate-list" should work even if one or few of the opaque type secrets data is None

Actual Behavior
----------------
When any of the k8s Opaque type secret data is None, the "system k8s-certificate-list" command fails

Reproducibility
---------------
100% reproducible.

System Configuration
--------------------
Any.

Branch/Pull Time/Commit
-----------------------
NA.

Last Pass
---------
NA.

Timestamp/Logs
--------------
NA.

Test Activity
-------------
NA.

Workaround
----------
NA

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/config/+/919885

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/config/+/919885
Committed: https://opendev.org/starlingx/config/commit/0e941dc7c21bab8dc01d9d94eae0eb3c38d6f16d
Submitter: "Zuul (22348)"
Branch: master

commit 0e941dc7c21bab8dc01d9d94eae0eb3c38d6f16d
Author: amantri <email address hidden>
Date: Thu May 16 12:25:34 2024 -0400

    Support secrets of data field with None

    Some of the k8s Opaque type secrets data has None values, this
    is failing the "system k8s-certificate-list" command.This fix
    addresses this issue by checking the "data" field in the
    secret

    Test Cases:
    Pass: Have a secret with no data, run "system k8s-certificate-
          list" comamnd and verify it is listing the certificates

    Closes-bug: 2065926

    Change-Id: I85ea4341d71016c6064b22860f761b3f77f1619c
    Signed-off-by: amantri <email address hidden>