add_cloud_init_test

[rmhsawyer]

Add test case for cloud-init to catch any "ERROR" or "WARNING" message in /var/log/cloud-init.log and also check if command "cloud-init status" return 0.

Limit the test only to CBLMariner.

[LiliDeng]

I ran the test against the ubuntu 2004, it failed.

If we see the warnings ['May 7 02:31:45 lisa--188-e0-n0 chronyd-starter.sh[732]: WARNING: libcap needs an update (cap=40 should have a name).\r', 'May 7 02:31:47 lisa--188-e0-n0 python3[957]: 2024-05-07T02:31:47.874209Z WARNING ExtHandler Dhcp client is not running.\r', what we should do next?

This one 'May 7 02:31:52 lisa--188-e0-n0 root: Added ephemeral disk warning to /mnt/DATALOSS_WARNING_README.txt\r'] is false alarm.

AzureImageStandard.verify_cloud_init_error_status: FAILED failed. AssertionError: [unexpected ERROR/WARNING shown up in cloud-init.log Ubuntu 20.4.0] Expected <['May 7 02:31:45 lisa--188-e0-n0 chronyd-starter.sh[732]: WARNING: libcap needs an update (cap=40 should have a name).\r', 'May 7 02:31:47 lisa--188-e0-n0 python3[957]: 2024-05-07T02:31:47.874209Z WARNING ExtHandler Dhcp client is not running.\r', 'May 7 02:31:52 lisa--188-e0-n0 root: Added ephemeral disk warning to /mnt/DATALOSS_WARNING_README.txt\r']> to be empty, but was not.

[rmhsawyer]

I've limited the test to Mariner only as the purpose of this change is for Mariner only to catch early regression and I did not explore the possible failing cases for other distros.

[squirrelsc]

@LiliDeng LGTM