Fixed a few issues with the build pipeline from the refactoring

[StephenHodgson]

XRTK - Mixed Reality Toolkit Pull Request

Overview

• Fixed a few issues with the build pipeline from the refactoring
• Removed logs from pre/post build steps

Submodule Changes

• https://github.com/XRTK/Lumin/pull/109
• https://github.com/XRTK/WindowsMixedReality/pull/137

[StephenHodgson]

/azp run

[azure-pipelines[bot]]

Azure Pipelines failed to run 1 pipeline(s).

[StephenHodgson]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).