Remove compression stat update from update script

Updating the compression stats can potentially be a very big task
locking many tables, so we remove it from the update script. We also
remove the check from the update test.

Fixes #2859

sql/updates/2.0.0-rc3--2.0.0-rc4.sql

@@ -127,37 +127,3 @@ ON DELETE CASCADE;
 GRANT SELECT ON _timescaledb_catalog.hypertable_id_seq TO PUBLIC;
 GRANT SELECT ON _timescaledb_catalog.hypertable TO PUBLIC;
 --End Modify hypertable table
-
--- update metadata for chunks compressed before 2.0
-DO $$
-DECLARE
-  plain_chunk RECORD;
-  comp_chunk TEXT;
-  rowcount_pre BIGINT;
-  rowcount_post BIGINT;
-BEGIN
-  FOR plain_chunk IN
-  SELECT
-    *
-  FROM
-    _timescaledb_catalog.chunk comp
-  WHERE
-    compressed_chunk_id IS NOT NULL LOOP
-      SELECT
-        format('%I.%I', schema_name, table_name) INTO comp_chunk
-      FROM
-        _timescaledb_catalog.chunk
-      WHERE
-        id = plain_chunk.compressed_chunk_id;
-      EXECUTE format('SELECT sum(_ts_meta_count), count(*) FROM %s', comp_chunk) INTO rowcount_pre, rowcount_post;
-      UPDATE
-        _timescaledb_catalog.compression_chunk_size
-      SET
-        numrows_pre_compression = rowcount_pre,
-        numrows_post_compression = rowcount_post
-      WHERE
-        chunk_id = plain_chunk.id;
-    END LOOP;
-END
-$$;
-

test/sql/updates/post.compression.sql

@@ -18,32 +18,3 @@ WHERE
   AND chunk.compressed_chunk_id IS NULL;
 
 SELECT * FROM compress ORDER BY time DESC, small_cardinality;
-
--- check count and approximate_row_count are the same after analyze
-ANALYZE compress;
-SELECT
-  count,
-  approximate,
-  CASE WHEN count != approximate THEN
-    'counts not matching' || random()::TEXT
-  ELSE
-    'match'
-  END AS MATCH
-FROM (
-  SELECT
-    count(*)
-  FROM
-    compress) AS count,
-  approximate_row_count('compress') AS approximate;
-
-SELECT
-  hypertable_schema,
-  hypertable_name,
-  approximate_row_count(format('%I.%I', hypertable_schema, hypertable_name)::REGCLASS)
-FROM
-  timescaledb_information.hypertables
-WHERE
-  compression_enabled = true
-ORDER BY
-  1,
-  2;