test: refine connection drain test (#2245)
test: refine connection drain test (#2245)

Description: Just makes the test a little more comprehensive. Had this as stashed state from my local testing of the feature and missed including it.
Risk Level: Low
Testing: Included

Signed-off-by: Mike Schore <270e364e708f2af319f244c09ceba52a03dbd980@gmail.com>
envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile