regression test: fix hot standby tests by using repeatable read

Serializable transactions won't work on a Hot Standby.  Also fix
VACUUM/ANALYZE label mixup.

Patch by Martín Marqués

src/test/regress/expected/hs_standby_allowed.out

@@ -49,7 +49,7 @@ select count(*)  as should_be_1 from hs1;
 (1 row)
 
 end;
-begin transaction isolation level serializable;
+begin transaction isolation level repeatable read;
 select count(*) as should_be_1 from hs1;
  should_be_1 
 -------------

src/test/regress/expected/hs_standby_disallowed.out

@@ -124,7 +124,7 @@ unlisten *;
 ERROR:  cannot execute UNLISTEN during recovery
 -- disallowed commands
 ANALYZE hs1;
-ERROR:  cannot execute VACUUM during recovery
+ERROR:  cannot execute ANALYZE during recovery
 VACUUM hs2;
 ERROR:  cannot execute VACUUM during recovery
 CLUSTER hs2 using hs1_pkey;

src/test/regress/sql/hs_standby_allowed.sql

@@ -28,7 +28,7 @@ begin transaction read only;
 select count(*)  as should_be_1 from hs1;
 end;
 
-begin transaction isolation level serializable;
+begin transaction isolation level repeatable read;
 select count(*) as should_be_1 from hs1;
 select count(*) as should_be_1 from hs1;
 select count(*) as should_be_1 from hs1;