Choco upgrade should preserve collector service custom env vars

[pjanotti]

Description:
Choco upgrade should preserve custom environment variables set by the user and should not fail if env vars contain double-quotes.

Link to Splunk idea:

• https://splunk.atlassian.net/browse/OTL-3041
• Follow-up to https://splunk.atlassian.net/browse/OTL-3017

Testing:

• Improved current test to include a "good env var" to be preserved and another "good env var" that needs to be escaped when passed in the invocation of the MSI installed.
• Manually testing the modified test via DNM: Test the test from fix choco upgrade with custom env vars #5388

Documentation:
N/A