Disable VsixInstaller.Tests on CI since it randomly hangs the build
Disable VsixInstaller.Tests on CI since it randomly hangs the build

Doing VSIX/VS integration tests is brittle. Turn off on CI, since we run
the tests locally anyway when changes happen on that nuget. It's not often
enough to guarantee running it always.

MobileEssentials/MSBuilder,kzu/MSBuilder