Removed unnecessary files created at project initialization

FullstackProsjekt/src/backend/main/java/edu/ntnu/idatt2105/controller/HelloController.java

-package edu.ntnu.idatt2105.controller;
-
-import org.springframework.http.HttpStatus;
-import org.springframework.http.ResponseEntity;
-import org.springframework.stereotype.Controller;
-import org.springframework.web.bind.annotation.RequestMapping;
-
-@Controller
-public class HelloController {
-
-    @RequestMapping("/")
-    public ResponseEntity<String> helloWorld(){
-        return new ResponseEntity<>("Hello", HttpStatus.OK);
-    }
-}
\ No newline at end of file