Fix ObjectType casing and conflict between Relation and RelationMetadata (#9849)

Fixes #9827 

Also uncovered a conflict with `@objectType('Relation')` and
`@objectType('relation)`

I don't want to address it in this PR so I will create a followup issue
when we close this but I think there's a confusion between
Relation/RelationMetadata, it's unclear what is what

---------

Co-authored-by: Antoine Moreaux <moreaux.antoine@gmail.com>

packages/twenty-server/src/engine/core-modules/messaging/dtos/timeline-thread-participant.dto.ts

@@ -2,7 +2,7 @@ import { Field, ObjectType } from '@nestjs/graphql';
 
 import { UUIDScalarType } from 'src/engine/api/graphql/workspace-schema-builder/graphql-types/scalars';
 
-@ObjectType('TimelineThreadParticipant')
+@ObjectType()
 export class TimelineThreadParticipant {
   @Field(() => UUIDScalarType, { nullable: true })
   personId: string | null;

packages/twenty-server/src/engine/core-modules/messaging/dtos/timeline-thread.dto.ts

@@ -4,7 +4,7 @@ import { UUIDScalarType } from 'src/engine/api/graphql/workspace-schema-builder/
 import { TimelineThreadParticipant } from 'src/engine/core-modules/messaging/dtos/timeline-thread-participant.dto';
 import { MessageChannelVisibility } from 'src/modules/messaging/common/standard-objects/message-channel.workspace-entity';
 
-@ObjectType('TimelineThread')
+@ObjectType()
 export class TimelineThread {
   @Field(() => UUIDScalarType)
   id: string;

packages/twenty-server/src/engine/core-modules/messaging/dtos/timeline-threads-with-total.dto.ts

@@ -2,7 +2,7 @@ import { Field, Int, ObjectType } from '@nestjs/graphql';
 
 import { TimelineThread } from 'src/engine/core-modules/messaging/dtos/timeline-thread.dto';
 
-@ObjectType('TimelineThreadsWithTotal')
+@ObjectType()
 export class TimelineThreadsWithTotal {
   @Field(() => Int)
   totalNumberOfThreads: number;