Making VQE tests lighter

[scarrazza]

This should prevent #1122.

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[stavros11]

Thanks. I cannot confirm about the issue but tests are also a bit faster now.

[scarrazza]

Thanks @stavros11, but I will keep this open until I identify which backend/setup is generating this issue in the CI.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1917462) 100.00% compared to head (8fb699e) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1144   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           67        67           
  Lines         9589      9589           
=========================================
  Hits          9589      9589           

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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[scarrazza]

Let me merge this now, I have switched off tensorflow on macos given that it is consuming a large number of resources.