Shorten hm polling interval for integration tests

Signed-off-by: Jesse Zhang <jz@pivotallabs.com>
More robust Health Monitor varz test

Use spin locking to be less time sensitive.

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Lower potential for port collision in integration tests

[Finishes #55339446]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>