[FIX] config: fix pg_dump not found

Issue

	- Remove ~/.odoorc
	- Launch a server
	- Try to dump the db in db manager

	Ok

	- Restart the server
	- Retry

	pg_dump not found

Cause

	When the .odoorc file is not there,
	the pg_path option is not present so
	the normalize method set it to None

	When the server is restarted, it re-checks
	the options (which are strings) and in the
	normalize method we check "if not pg_path"
	but 'None' is truthy so it thinks this is
	a real path.

Solution

	Check if not pg_path or if pg_path string
	is None

OPW-2189789

closes #45354

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

odoo/tools/config.py

@@ -710,7 +710,7 @@ def verify_admin_password(self, password):
 
     def _normalize(self, path):
         if not path:
-            return path
+            return ''
         return realpath(abspath(expanduser(expandvars(path.strip()))))