[Backend] Remove support for passing hash for variantAutocomplete

Instead, pass only

    searchParameters: function (_selectSearchTerm) { return { suppliable_only: true  } }

Ref solidusio#4767

backend/app/assets/javascripts/spree/backend/variant_autocomplete.js

@@ -21,18 +21,6 @@
  if (typeof(options) === 'object') {
  if (typeof(options['searchParameters']) === 'function') {
  return options['searchParameters'](term)
- } else {
- console.warn(
- "Solidus deprecation: Passing an object of parameters to variantAutocomplete is deprecated. Instead, on the options object, please declare `searchParameters` as a function returning the parameters.\n\n",
- "Deprecated usage:\n",
- "$('#id').variantAutocomplete({\n",
- " suppliable_only: true\n",
- "})",
- "\n\nNew usage:\n",
- "$('#id').variantAutocomplete({\n",
- " searchParameters: function (_selectSearchTerm) { return { suppliable_only: true } }\n",
- "})"
- )
  }
  }