Introspection doesn't work with pg driver on AWS redshift serverless db

```txt
[✓] 1 tables fetched
[⣯] 0 columns fetching
[⣯] 0 enums fetching
[⣯] 0 indexes fetching
[⣯] 0 foreign keys fetching

error: syntax error at or near "FROM"

length: 131,
severity: 'ERROR',
code: '42601',
detail: undefined,
hint: undefined,
position: '208',
internalPosition: undefined,
internalQuery: undefined,
where: undefined,
schema: undefined,
table: undefined,
column: undefined,
dataType: undefined,
constraint: undefined,
file: '/home/ec2-user/padb/src/pg/src/backend/parser/parser_scan.l',
line: '821',
routine: 'yyerror'
```

Start by reproducing introspection against an AWS Redshift Serverless database with the pg driver and capture the SQL that produces the syntax error near FROM. Trace the introspection query responsible for columns, enums, indexes, or foreign keys; done means introspection completes without the reported 42601 error and fetches those metadata sections.

Written by the indexing model from the issue text.