Flake in TestMain of pkg/package-server/provider

[benluddy]

net.Listen sometimes returns EADDRINUSE during TestMain at https://github.com/operator-framework/operator-lifecycle-manager/blob/master/pkg/package-server/provider/registry_test.go#L48.

Seen in https://prow.ci.openshift.org/view/gs/origin-ci-test/pr-logs/pull/openshift_operator-framework-olm/85/pull-ci-openshift-operator-framework-olm-master-unit-olm/1402717321759297536#1:build-log.txt%3A419:

time="2021-06-09T20:08:13Z" level=fatal msg="failed to listen: listen tcp 127.0.0.1:50054: bind: address already in use" 
FAIL	github.com/operator-framework/operator-lifecycle-manager/pkg/package-server/provider	0.071s