Increase OpenMRS test docker image pull limit.

[bashir2]

When running multiple e2e tests, we soon get an error like the following when starting OpenMRS here:

16358E2E: BATCH MODE TEST: STARTING SERVERs
16359Creating network "docker_default" with the default driver
16360Pulling mysql (mysql:5.7)...
16361ERROR: toomanyrequests: You have reached your pull rate limit. You may increase the limit by authenticating and upgrading: https://www.docker.com/increase-rate-limit
16362E2E: BATCH MODE TEST: WAITING FOR OPENMRS SERVER TO START
16363E2E: BATCH MODE TEST: WAITING FOR OPENMRS SERVER TO START
16364E2E: BATCH MODE TEST: WAITING FOR OPENMRS SERVER TO START

which eventually fails the e2e test. This seems to be triggered by fetching ampathke/openmrs-reference-application-distro:analytics here. One solution is to recreated the image and move it to somewhere else, e.g., a GCE container registry with no such limits.

[bashir2]

I have not seen this error in a long time; lowering priority.