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-server/src/engine/twenty-orm/utils/split-classes-and-strings.util.ts

@@ -1,8 +0,0 @@
-export const splitClassesAndStrings = <T>(
-  classesAndStrings: (string | T)[],
-): [T[], string[]] => {
-  return [
-    classesAndStrings.filter((cls): cls is T => typeof cls !== 'string'),
-    classesAndStrings.filter((str): str is string => typeof str === 'string'),
-  ];
-};