chore(*): remove unused code (#6781)

The code removed in the PR was flagged as unused by the JetBrains
inspector.

I did a QA on the dev environment but other checks are highly
recommended.

There is one commit by scope to make the review easier.

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/engine/metadata-modules/relation-metadata/hooks/before-create-one-relation.hook.ts

@@ -9,7 +9,7 @@ import { CreateRelationInput } from 'src/engine/metadata-modules/relation-metada
 
 @Injectable()
 export class BeforeCreateOneRelation<T extends CreateRelationInput>
-  implements BeforeCreateOneHook<T, any>
+  implements BeforeCreateOneHook<T>
 {
   async run(
     instance: CreateOneInputType<T>,

packages/twenty-server/src/engine/metadata-modules/relation-metadata/hooks/before-delete-one-relation.hook.ts

@@ -12,7 +12,7 @@ import {
 import { RelationMetadataService } from 'src/engine/metadata-modules/relation-metadata/relation-metadata.service';
 
 @Injectable()
-export class BeforeDeleteOneRelation implements BeforeDeleteOneHook<any> {
+export class BeforeDeleteOneRelation implements BeforeDeleteOneHook {
   constructor(readonly relationMetadataService: RelationMetadataService) {}
 
   async run(