fix: fix entityManager.getId for custom join table

getId currently returns undefined for an entity with composite primary
key if primary key columns also foreign keys with lazy relations,
for e.g., in a custom join table. This commit tries to fix that

Closes: typeorm#7736 (maybe)

src/metadata/ColumnMetadata.ts

@@ -570,7 +570,7 @@ export class ColumnMetadata {
             return Object.keys(map).length > 0 ? map : undefined;
 
         } else { // no embeds - no problems. Simply return column property name and its value of the entity
-            if (this.relationMetadata && entity[this.relationMetadata.propertyName] && entity[this.relationMetadata.propertyName] instanceof Object) {
+            if (this.relationMetadata && !Object.getOwnPropertyDescriptor(entity, this.relationMetadata.propertyName)?.get && entity[this.relationMetadata.propertyName] && entity[this.relationMetadata.propertyName] instanceof Object) {
                 const map = this.relationMetadata.joinColumns.reduce((map, joinColumn) => {
                     const value = joinColumn.referencedColumn!.getEntityValueMap(entity[this.relationMetadata!.propertyName]);
                     if (value === undefined) return map;