Unable to run queries against multi-level abstract classes

[parisholley]

Describe the bug
Given the following model:

abstract class BaseMikro {
  @PrimaryKey({ type: 'bigint' })
  id!: string;
}

@Entity({ discriminatorColumn: 'type', abstract: true })
abstract class LevelOne extends BaseMikro {
  @Property({ type: 'int' })
  type!: number;
}

@Entity({ abstract: true })
abstract class LevelTwo extends LevelOne {
  @PrimaryKey({ type: 'bigint' })
  id!: string;

  @Property()
  name!: string;
}

@Entity({ discriminatorValue: 1 })
export class LevelThree extends LevelTwo {
  @PrimaryKey({ type: 'bigint' })
  id!: string;

  @Property()
  name!: string;
}

Doing a find like so

orm.em.find(LevelTwo, {});

Stack trace

    MetadataError: Metadata for entity LevelTwo not found

      211 |
      212 |   static missingMetadata(entity: string): MetadataError {
    > 213 |     return new MetadataError(`Metadata for entity ${entity} not found`);
          |            ^
      214 |   }
      215 |
      216 |   static conflictingPropertyName(className: string, name: string, embeddedName: string): MetadataError {

      at Function.missingMetadata (packages/core/src/errors.ts:213:12)
      at MetadataStorage.get (packages/core/src/metadata/MetadataStorage.ts:78:27)
      at SqlEntityManager.tryFlush (packages/core/src/EntityManager.ts:991:30)
      at SqlEntityManager.find (packages/core/src/EntityManager.ts:115:14)
      at Object.<anonymous> (tests/issues/GH3743.test.ts:49:16)