Fix breakages of hot standby regression test.

This commit changes HS regression test so that it uses
REPEATABLE READ transaction instead of SERIALIZABLE one
because SERIALIZABLE transaction isolation level is not
available in HS. Also this commit fixes VACUUM/ANALYZE
label mixup.

This was fixed in HEAD (commit 2985e16), but it should
have been back-patched to 9.1 which had introduced SSI
and forbidden SERIALIZABLE transaction in HS.

Amit Langote

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;