Do not update goal state from main loop in monitor thread

[narrieta]

The monitor thread and the extension handler thread may try to update the certificates from the goal state concurrently, which can produce sporadic failures.

The main loop in monitor actually does not need to update the full goal state; the only data it needs are the container id and role config name to keep the host ga plugin up to date (to send the plugin's hearbeat).

There is a small chance of a race condition during initialization: MonitorHandler.init_protocols calls update_goal_state. I will address that issue on a separate PR.

Verified the fix manually using the debugger on a live VM.

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This change is 

[codecov]

Codecov Report

Merging #1767 into develop will decrease coverage by <.01%.
The diff coverage is 57.14%.

@@             Coverage Diff             @@
##           develop    #1767      +/-   ##
===========================================
- Coverage    69.17%   69.16%   -0.01%     
===========================================
  Files           82       82              
  Lines        11726    11732       +6     
  Branches      1645     1645              
===========================================
+ Hits          8111     8114       +3     
- Misses        3263     3266       +3     
  Partials       352      352

Impacted Files	Coverage Δ
azurelinuxagent/ga/monitor.py	93.91% <100%> (ø)	⬆️
azurelinuxagent/common/protocol/restapi.py	87.5% <50%> (-0.46%)	⬇️
azurelinuxagent/common/protocol/wire.py	77.77% <50%> (-0.06%)	⬇️
azurelinuxagent/common/protocol/metadata.py	53.31% <50%> (-0.03%)	⬇️

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