Search UI/API - Remove other reasons component in SI filing

Solicitors have advised that we should not collect "Other reasons" why a person is an SI. In the event the legislation or regulations outlined additional reasons a person may be defined as an SI we would be best to update the for to more specifically include those options.

- remove from UI filter
- cleanup so we no longer have reference to other reasons
- QA Note: QA should be done to verify the filter for 'Other Reasons' does not show

**Change: remove from search results**

Start by locating the search UI filter and API/search-results handling for the "Other Reasons" option. Remove the option and remaining references, then verify through QA that "Other Reasons" no longer appears in the filter or search results.

Written by the indexing model from the issue text.