Squash data from all threads before inserting

Squash data from all threads before inserting to materialized views depending on the settings min_insert_block_size_rows_for_materialized_views and min_insert_block_size_bytes_for_materialized_views. Previously, if parallel_view_processing was enabled, each thread inserting to a specific materailized view would squash insert independently which could lead to higher number of generated parts. #87280 (Antonio Andelic).