Fix issues related to Querydsl 5.0 upgrade.

Remove overridden methods no longer available in public api.

Closes: #3738

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/support/QuerydslAbstractMongodbQuery.java

@@ -177,16 +177,6 @@ protected Document createSort(List<OrderSpecifier<?>> orderSpecifiers) {
 		return serializer.toSort(orderSpecifiers);
 	}
 
-	/**
-	 * Get the actual {@link QueryMixin} delegate.
-	 *
-	 * @return
-	 */
-	QueryMixin<Q> getQueryMixin() {
-		return queryMixin;
-	}
-
-
 	/**
 	 * Returns the {@literal Mongo Shell} representation of the query. <br />
 	 * The following query

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/repository/support/SpringDataMongodbQuerySupport.java

@@ -139,9 +139,4 @@ public String toJson(JsonWriterSettings settings) {
 	protected Document createSort(List<OrderSpecifier<?>> orderSpecifiers) {
 		return serializer.toSort(orderSpecifiers);
 	}
-
-	// TODO: Remove once https://github.com/querydsl/querydsl/pull/2916 is merged
-	QueryMixin<Q> getQueryMixin() {
-		return superQueryMixin;
-	}
 }