fix: CI failed plpython and plpython3

[yihong0618]

Here are some reminders before you submit the pull request

• Add tests for the change
• Document changes
• Communicate in the mailing list if needed
• Pass make installcheck
• Review a PR in return to support the community

---

This is based the PR https://github.com/greenplum-db/gpdb/pull/13095

• fix the plpython Ci failed
• based on the difference python2 and python3 created two files plpython_returns_2.out and plpython_returns_3.out for the different behavior of these
• change the Makefile for support the plpython3 install_check
• change the init_file for the uselesss diff

[beeender]

Please take a note of the reasons for python3 test case changes. We need to summarize it in our final commit message.

[beeender]

this line can be removed

[beeender]

why this is needed? I think the plpython_returns.out is for python2?

[beeender]

I think we don't need this file

[beeender]

This doesn't work on my computer. It should not be a big deal as long as it passes on our CI.

❯ python3 --version
Python 3.10.2

--- \/home\/cc\/repo\/gpdb6\/src\/pl\/plpython3\/expected\/python3\/plpython_returns\.out       2022-03-25 20:19:38.405854360 +0800
+++ \/home\/cc\/repo\/gpdb6\/src\/pl\/plpython3\/results\/python3\/plpython_returns\.out        2022-03-25 20:19:38.424854218 +0800
@@ -1977,7 +1977,7 @@
 (1 row)

 SELECT * FROM test_return_table_record('{"first": "value", "second": 4}, "third": "ignored"}');
-ERROR:  SyntaxError: invalid syntax (<string>, line 1)
+ERROR:  SyntaxError: unmatched '}' (<string>, line 1)
 -- =====================================================
 -- TEST 4:  RETURN VALUE TESTING - SETOF Compound values
 -- =====================================================
@@ -2093,7 +2093,7 @@
 SELECT test_return_setof_type_record('[{"first": "value", "second": 4, "third": "ignored"}]');

 SELECT * FROM test_return_setof_type_record('[{"first": "value", "second": 4}, "third": "ignored"}]');
-ERROR:  SyntaxError: invalid syntax (<string>, line 1)
+ERROR:  SyntaxError: closing parenthesis '}' does not match opening parenthesis '[' (<string>, line 1)
 --
 -- Case 2: From a setof Table Type
 --
@@ -2200,7 +2200,7 @@
 SELECT test_return_setof_table_record('[{"first": "value", "second": 4, "third": "ignored"}]');

 SELECT * FROM test_return_setof_table_record('[{"first": "value", "second": 4}, "third": "ignored"}]');
-ERROR:  SyntaxError: invalid syntax (<string>, line 1)
+ERROR:  SyntaxError: closing parenthesis '}' does not match opening parenthesis '[' (<string>, line 1)
 -- =====================================================
 -- TEST 5:  RETURN VALUE TESTING - OUT Parameters
 -- =====================================================
@@ -2896,7 +2896,7 @@
 (1 row)

 SELECT * FROM test_return_out_setof_record('[{"first": "value", "second": 4}, "third": "ignored"}]');
-ERROR:  SyntaxError: invalid syntax (<string>, line 1)
+ERROR:  SyntaxError: closing parenthesis '}' does not match opening parenthesis '[' (<string>, line 1)
 -- From Python List of String (one character per column)
 SELECT test_return_out_setof_record('["a4"]');
 ERROR:  malformed record literal: "a4"

======================================================================

[beeender]

I think this line is not needed since we have line 174?
Plus this will create a git diff which is not ideal:

❯ git status
On branch hy/plpython3
Your branch is up to date with 'beeender/hy/plpython3'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
        modified:   ../../backend/utils/error/elog.c
        modified:   ../plpython/expected/plpython_returns.out

[beeender]

I don't think this is needed since python3's expected is always in expected/python3/plpython_types.out