Change integration tests environment variables + add option

[montezdesousa]

Description

• OPENBB_ENABLE_QUICK_EXIT=False ensures tests run
• OPENBB_USE_ION=True ensures tests don't hang if --subproc > 0, otherwise we have to close plots manually to continue with the script
• Added option to run tests sequentially without being verbose, e.g. python terminal.py -t --subproc 0

• Summary of the change / bug fix.
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How has this been tested?

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• Make sure affected commands still run in terminal
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Checklist:

• Update our Hugo documentation following these guidelines.
• Update our tests following these guidelines.
• Make sure you are following our CONTRIBUTING guidelines.
• If a feature was added make sure to add it to the corresponding scripts file.

Others

• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.