Remove useless and rather expensive stanza in matview regression test.

This removes a test case added by commit b69ec7cc, which was intended
to exercise a corner case involving the rule used at that time that
materialized views were unpopulated iff they had physical size zero.
We got rid of that rule very shortly later, in commit 1d6c72a5, but
kept the test case.  However, because the case now asks what VACUUM
will do to a zero-sized physical file, it would be pretty surprising
if the answer were ever anything but "nothing" ... and if things were
indeed that broken, surely we'd find it out from other tests.  Since
the test involves a table that's fairly large by regression-test
standards (100K rows), it's quite slow to run.  Dropping it should
save some buildfarm cycles, so let's do that.

Discussion: https://postgr.es/m/32386.1493831320@sss.pgh.pa.us

src/test/regress/expected/matview.out

@@ -382,26 +382,6 @@ NOTICE:  drop cascades to 3 other objects
 DETAIL:  drop cascades to view mvtest_vt2
 drop cascades to materialized view mv_test2
 drop cascades to materialized view mv_test3
--- test that vacuum does not make empty matview look unpopulated
-CREATE TABLE mvtest_huge (i int);
-INSERT INTO mvtest_huge VALUES (generate_series(1,100000));
-CREATE MATERIALIZED VIEW mvtest_hugeview AS SELECT * FROM mvtest_huge WHERE i % 2 = 0;
-CREATE INDEX mvtest_hugeviewidx ON mvtest_hugeview (i);
-DELETE FROM mvtest_huge;
-REFRESH MATERIALIZED VIEW mvtest_hugeview;
-SELECT * FROM mvtest_hugeview WHERE i < 10;
- i 
----
-(0 rows)
-
-VACUUM ANALYZE mvtest_hugeview;
-SELECT * FROM mvtest_hugeview WHERE i < 10;
- i 
----
-(0 rows)
-
-DROP TABLE mvtest_huge CASCADE;
-NOTICE:  drop cascades to materialized view mvtest_hugeview
 -- test that duplicate values on unique index prevent refresh
 CREATE TABLE mvtest_foo(a, b) AS VALUES(1, 10);
 CREATE MATERIALIZED VIEW mvtest_mv AS SELECT * FROM mvtest_foo;

src/test/regress/sql/matview.sql

@@ -122,18 +122,6 @@ SELECT relispopulated FROM pg_class WHERE oid = 'mv_test3'::regclass;
 
 DROP VIEW mvtest_vt1 CASCADE;
 
--- test that vacuum does not make empty matview look unpopulated
-CREATE TABLE mvtest_huge (i int);
-INSERT INTO mvtest_huge VALUES (generate_series(1,100000));
-CREATE MATERIALIZED VIEW mvtest_hugeview AS SELECT * FROM mvtest_huge WHERE i % 2 = 0;
-CREATE INDEX mvtest_hugeviewidx ON mvtest_hugeview (i);
-DELETE FROM mvtest_huge;
-REFRESH MATERIALIZED VIEW mvtest_hugeview;
-SELECT * FROM mvtest_hugeview WHERE i < 10;
-VACUUM ANALYZE mvtest_hugeview;
-SELECT * FROM mvtest_hugeview WHERE i < 10;
-DROP TABLE mvtest_huge CASCADE;
-
 -- test that duplicate values on unique index prevent refresh
 CREATE TABLE mvtest_foo(a, b) AS VALUES(1, 10);
 CREATE MATERIALIZED VIEW mvtest_mv AS SELECT * FROM mvtest_foo;