[2.0.x] Improve timeouts occurring on Anka builds.

[scottarnette]

Change Description

Updating parameters in the Anka Buildkite plugin to alleviate the increase in timeouts we see on Mac related build/test steps.

• Adds short explicit sleep before continuing to git clone steps.
• Adds ping to Github that must pass before continuing to git clone steps.

Change Type

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Testing Changes

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