refactor: always set AZURE_ENVIRONMENT_FILEPATH on windows in custom cloud environments

[cameronmeissner]

What type of PR is this?

Always set AZURE_ENVIRONMENT_FILEPATH on windows node when custom cloud is configured for AGC.

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Requirements:

• [ ] uses conventional commit messages
• [ ] includes documentation
• [ ] adds unit tests
• [ ] tested upgrade from previous version

Special notes for your reviewer:

Release note:

none

[coveralls]

Pull Request Test Coverage Report for Build 6836045784

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 79.007%

---

Totals
Change from base Build 6835408678:	0.0%
Covered Lines:	2243
Relevant Lines:	2839

---

💛 - Coveralls