Refs #238. Update CRM_Mailchimp_Sync::SplitMailchimpWebhookGroupsToCiviGroupIds() to pass tests with observed inputs.
Refs #238. Update CRM_Mailchimp_Sync::SplitMailchimpWebhookGroupsToCiviGroupIds() to pass tests with observed inputs.

krishgopi/uk.co.vedaconsulting.mailchimp,veda-consulting/uk.co.vedaconsulting.mailchimp,krishgopi/uk.co.vedaconsulting.mailchimp,artfulrobot/uk.co.vedaconsulting.mailchimp,artfulrobot/uk.co.vedaconsulting.mailchimp,veda-consulting/uk.co.vedaconsulting.mailchimp