Fix some more regression test row-order-instability issues.

Commit 0563a3a8 just introduced another instance of the same unsafe
testing methodology that appeared in 2ac3ef7a, which I corrected in
257d8157.  Robert/Amit, please stop doing that.

Also look through the rest of f0e44751's test cases, and correct some
other queries with underdetermined ordering of results from the system
catalogs.  These haven't failed in the buildfarm yet, but I don't
have any confidence in that staying true.

Per multiple buildfarm members.

src/test/regress/expected/alter_table.out

@@ -3353,7 +3353,8 @@ from pg_attribute
 where attname = 'a'
  and (attrelid = 'p'::regclass
    or attrelid = 'p1'::regclass
-   or attrelid = 'p11'::regclass);
+   or attrelid = 'p11'::regclass)
+order by attrelid::regclass::text;
  attrelid | attname | attnum 
 ----------+---------+--------
  p        | a       |      1

src/test/regress/expected/create_table.out

@@ -400,7 +400,9 @@ SELECT relkind FROM pg_class WHERE relname = 'partitioned';
 (1 row)
 
 -- check that range partition key columns are marked NOT NULL
-SELECT attname, attnotnull FROM pg_attribute WHERE attrelid = 'partitioned'::regclass AND attnum > 0;
+SELECT attname, attnotnull FROM pg_attribute
+  WHERE attrelid = 'partitioned'::regclass AND attnum > 0
+  ORDER BY attnum;
  attname | attnotnull 
 ---------+------------
  a       | t
@@ -575,7 +577,9 @@ CREATE TABLE parted (
 ) PARTITION BY LIST (a);
 CREATE TABLE part_a PARTITION OF parted FOR VALUES IN ('a');
 -- only inherited attributes (never local ones)
-SELECT attname, attislocal, attinhcount FROM pg_attribute WHERE attrelid = 'part_a'::regclass and attnum > 0;
+SELECT attname, attislocal, attinhcount FROM pg_attribute
+  WHERE attrelid = 'part_a'::regclass and attnum > 0
+  ORDER BY attnum;
  attname | attislocal | attinhcount 
 ---------+------------+-------------
  a       | f          |           1

src/test/regress/sql/alter_table.sql

@@ -2206,7 +2206,8 @@ from pg_attribute
 where attname = 'a'
  and (attrelid = 'p'::regclass
    or attrelid = 'p1'::regclass
-   or attrelid = 'p11'::regclass);
+   or attrelid = 'p11'::regclass)
+order by attrelid::regclass::text;
 
 alter table p1 attach partition p11 for values from (2) to (5);
 

src/test/regress/sql/create_table.sql

@@ -403,7 +403,9 @@ CREATE TABLE partitioned (
 SELECT relkind FROM pg_class WHERE relname = 'partitioned';
 
 -- check that range partition key columns are marked NOT NULL
-SELECT attname, attnotnull FROM pg_attribute WHERE attrelid = 'partitioned'::regclass AND attnum > 0;
+SELECT attname, attnotnull FROM pg_attribute
+  WHERE attrelid = 'partitioned'::regclass AND attnum > 0
+  ORDER BY attnum;
 
 -- prevent a function referenced in partition key from being dropped
 DROP FUNCTION plusone(int);
@@ -548,7 +550,9 @@ CREATE TABLE parted (
 CREATE TABLE part_a PARTITION OF parted FOR VALUES IN ('a');
 
 -- only inherited attributes (never local ones)
-SELECT attname, attislocal, attinhcount FROM pg_attribute WHERE attrelid = 'part_a'::regclass and attnum > 0;
+SELECT attname, attislocal, attinhcount FROM pg_attribute
+  WHERE attrelid = 'part_a'::regclass and attnum > 0
+  ORDER BY attnum;
 
 -- able to specify column default, column constraint, and table constraint
 CREATE TABLE part_b PARTITION OF parted (