fix: update global env in collection runner

[pooja-bruno]

Description

Addressing issue #4100

This PR fixes an issue where global environment variables set using bru.setGlobalEnvVar() in test scripts were not being saved correctly during a collection run.

What was the issue?

• When running multiple requests in a collection, if a test script updated a global environment variable, the next request didn't see the updated value.
• This issue only happened with test scripts. Pre-request and post-response scripts were already working fine.

Contribution Checklist:

• The pull request only addresses one issue or adds one feature.
• The pull request does not introduce any breaking changes
• I have added screenshots or gifs to help explain the change if applicable.
• I have read the [contribution guidelines]
• Create an issue and link to the pull request.

Screen.Recording.2025-02-28.at.11.45.02.AM.mov

[naman-bruno]

LGTM

[helloanoop]

Merged, Thanks @pooja-bruno !

Thanks @naman-bruno and @lohit-bruno for the review.