Refresh host ga plugin in periodic task

[narrieta]

Refreshing the goal state for the Host GA Plugin doesn't need to be done in the main method of the monitor thread. Moved it to the periodic task for the plugin.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (develop@21fd3c6). Click here to learn what that means.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             develop    #2155   +/-   ##
==========================================
  Coverage           ?   70.47%           
==========================================
  Files              ?       95           
  Lines              ?    13058           
  Branches           ?     1857           
==========================================
  Hits               ?     9203           
  Misses             ?     3442           
  Partials           ?      413           

Impacted Files	Coverage Δ
azurelinuxagent/ga/monitor.py	76.51% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 21fd3c6...fc82a56. Read the comment docs.