Remove some dead code (#6611)

We could remove a lot more than this, this is just a start.

There are various tools to help with this, knip is a good one

packages/twenty-front/src/modules/object-record/relation-picker/constants/CreateButtonId.ts

@@ -1 +0,0 @@
-export const CREATE_BUTTON_ID = 'create-button';

packages/twenty-front/src/modules/object-record/relation-picker/constants/EmptyButtonId.ts

@@ -1 +0,0 @@
-export const EMPTY_BUTTON_ID = 'empty-button';

packages/twenty-front/src/modules/object-record/relation-picker/utils/getPreselectedIdIndex.ts

@@ -1,10 +0,0 @@
-export const getPreselectedIdIndex = (
-  selectableOptionIds: string[],
-  preselectedOptionId: string,
-) => {
-  const preselectedIdIndex = selectableOptionIds.findIndex(
-    (option) => option === preselectedOptionId,
-  );
-
-  return preselectedIdIndex === -1 ? 0 : preselectedIdIndex;
-};