Change start date and change completion date are not searchable by default

Issue Summary

The "Change Start date" and "Change Completion date" fields in Jira Service Desk have no Search Template set when first installing JSD to Jira. As a result they don't show as fields in the issue searching menu and don't respond to jql autofill. 

Steps to Reproduce

1. Create a "Change" event in Jira Service Desk and add Change Start Date and Change Completion date fields.
2. Go to Search for Issues and look for the fields under the "more" dropdown - they don't show.
3. Under advanced search, try to add the fields into the jql: they don't show up under autocomplete and are invalid jql.

Expected Results

The "Change start date" and "Change completion date" would have search template set to "Date Time Range picker" by default.

Actual Results

The Change start date and Change completion date aren't searchable by default.

Workaround

1. Navigate to the admin issues tab and select "Custom Fields" from the side menu.
2. Search for "Change" to bring up the Change Start Date and Change Completion Date in the list.
3. Select "edit" from the cog icon beside each field to edit the Search Template.
4. Select "Date Time Range picker" from the dropdown menu for Search Template.
5. After completing this step for both fields, Reindex Jira.