Don't fire PR pipelines for the VMR unified build as well

[baronfel]

Like #43940, but also works for the VMR pipeline.

[MichaelSimons]

Why is this needed? Wasn't this change included in #43940?

[baronfel]

Chatting with @ellahathaway on Teams, my confusion was because the UB pipelines were still running on a PR I thought wouldn't trigger them (#43938), and she's checking why they still fired.

[baronfel]

This PR was made because I am a dummy that doesn't know how to properly sync branches before making changes.

[ellahathaway]

Chatting with @ellahathaway on Teams, my confusion was because the UB pipelines were still running on a PR I thought wouldn't trigger them (#43938), and she's checking why they still fired.

Followed up in teams - it was still triggering because we were manually overriding the triggers for the UB pipeline via the Azdo UI. I've manually added the exclusion paths via the UI, so the triggers should work as expected now.