Removing ability to invoke walinuxagent from cloud-init

[anhvoms]

Proposed Commit Message

azure: removing ability to invoke walinuxagent from within cloud-init as this is no longer supported/necessary.

Additional Context

Test Steps

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Overall this looks good. Is there a reason we can't also remove the other agent references? In DataSourceAzure.py, I'm looking at lines:
51,52,258,1254-1255

Should we still be defaulting data_dir to the AGENT_SEED_DIR (259)?
Is 'x-ms-agent-name': 'WALinuxAgent', still a valid header in azure.py (348)?
I still see a ton of waagent references in test_azure.py. Are all of those still valid?

We should also update doc/rtd/topics/datasources/azure.rst accordingly.

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging mitechie, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag mitechie to reopen it.)

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging mitechie, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag mitechie to reopen it.)

[anhvoms]

Overall this looks good. Is there a reason we can't also remove the other agent references? In DataSourceAzure.py, I'm looking at lines:
51,52,258,1254-1255

Should we still be defaulting data_dir to the AGENT_SEED_DIR (259)?
Is 'x-ms-agent-name': 'WALinuxAgent', still a valid header in azure.py (348)?
I still see a ton of waagent references in test_azure.py. Are all of those still valid?

We should also update doc/rtd/topics/datasources/azure.rst accordingly.

@TheRealFalcon
Re:data_dir: while we're removing the ability to invoke waagent from within cloud-init, waagent still manages extension handling for the VM and still depends on some artifacts from cloud-init. The data_dir is where the cloud-init caches the ovf-env.xml file in case of reboot during provisioning process. Waagent will also look into this directory for this file to know that cloud-init has proceeded to a certain stage of provisioning.
The header is still valid (some analyzers in the backend still look for this header)
The references in the test_azure.py are also valid

I will update the doc in azure.rst

[TheRealFalcon]

Thanks @anhvoms , this looks good.