Mdd psql user aws fix (#23988)

* postgresql_user module - transaction logic hacks to allow recovery from failed select

* postgresql_user - PEP8 and style fixes to make debugging easier

* postgresql_user - move password changing logic to separate function

* postgresql_user - trap failure in case where there is no access to pg_authid

* postgresql_user - further PEP8 fixes

* postgresql_user - Simplify password change logic and improve imports according to suggestions from PR review

* postgresql_user - Eliminate pep8/blank line errors introduced in merge

* Check behaviour when pg_authid relation isn't readable

TASK [postgresql : Normal user isn't allowed to access pg_authid relation:
      password comparison will fail, password will be updated] ***
An exception occurred during task execution. To see the full traceback,
use -vvv. The error was: psycopg2.ProgrammingError: permission denied
for relation pg_authid

* Don't reintroduce passlib, remove useless query

test/integration/targets/postgresql/tasks/main.yml

@@ -336,16 +336,21 @@
   become: True
   shell: echo "create table test_table2 (field text);" | psql {{ db_name }}
 
-- name: Create a user with some permissions on the db
-  become_user: "{{ pg_user }}"
-  become: True
-  postgresql_user:
-    name: "{{ db_user1 }}"
-    encrypted: 'yes'
-    password: "md55c8ccfd9d6711fc69a7eae647fc54f51"
-    db: "{{ db_name }}"
-    priv: 'test_table1:INSERT,SELECT,UPDATE,DELETE,TRUNCATE,REFERENCES,TRIGGER/test_table2:INSERT/CREATE,CONNECT,TEMP'
-    login_user: "{{ pg_user }}"
+- vars:
+    db_password: 'secretù' # use UTF-8
+  block:
+    - name: Create a user with some permissions on the db
+      become_user: "{{ pg_user }}"
+      become: True
+      postgresql_user:
+        name: "{{ db_user1 }}"
+        encrypted: 'yes'
+        password: "md5{{ (db_password ~ db_user1) | hash('md5')}}"
+        db: "{{ db_name }}"
+        priv: 'test_table1:INSERT,SELECT,UPDATE,DELETE,TRUNCATE,REFERENCES,TRIGGER/test_table2:INSERT/CREATE,CONNECT,TEMP'
+        login_user: "{{ pg_user }}"
+
+    - include: pg_authid_not_readable.yml
 
 - name: Check that the user has the requested permissions (table1)
   become_user: "{{ pg_user }}"