Temporarily disable get vmsize while UTs are hanging

[kevinclark19a]

Description

The VMSize heartbeat reporting added in #2462 is hanging UTs ran on non-Azure VM systems. This PR is meant to temporarily disable this reporting until #2513 can be merged and fix the bug.

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PR information

• The title of the PR is clear and informative.
• There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
• If applicable, the PR references the bug/issue that it fixes in the description.
• New Unit tests were added for the changes made

Quality of Code and Contribution Guidelines

• I have read the contribution guidelines.

[codecov]

Codecov Report

Merging #2515 (f15f548) into develop (9a11fa9) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #2515      +/-   ##
===========================================
- Coverage    71.85%   71.84%   -0.02%     
===========================================
  Files          101      101              
  Lines        15112    15112              
  Branches      2397     2397              
===========================================
- Hits         10859    10857       -2     
- Misses        3767     3772       +5     
+ Partials       486      483       -3     

Impacted Files	Coverage Δ
azurelinuxagent/ga/update.py	87.74% <100.00%> (-0.87%)	⬇️
azurelinuxagent/common/utils/restutil.py	84.03% <0.00%> (-0.33%)	⬇️
azurelinuxagent/common/event.py	86.03% <0.00%> (+0.67%)	⬆️
azurelinuxagent/ga/collect_telemetry_events.py	91.43% <0.00%> (+1.71%)	⬆️

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