Duckdb Polaris Integration does not support multi-tenant with Polaris-Realm header #978

Is your feature request related to a problem? Please describe.
I deployed duckdb and polaris to query iceberg table. The Polaris manage multi-tenant with Polaris Realms. But when using EXTRA_HTTP_HEADERS MAP {'Polaris-Realm': 'REALM1'}, it call Polaris instance with default realm rather than realm in the header.

Describe the solution you'd like
It need to handle Polaris-Realm to enable multi-tenant in Polaris integration.

Additional context
duckdb.sql('''
ATTACH 'my_catalog' AS my_catalog (
TYPE iceberg,
ACCESS_DELEGATION_MODE 'vended_credentials',
ENDPOINT 'xxx',
CLIENT_ID 'xxx',
CLIENT_SECRET 'xxx',
OAUTH2_SERVER_URI 'xxx/v1/oauth/tokens',
EXTRA_HTTP_HEADERS MAP {'Polaris-Realm': 'REALM1'}
);
''')

But from polaris log, it handle with default polaris is POLARIS.