[Bug]: duplicate extension load

[konsPolydorou]

What happened?

When Superset reuses the same connection, DuckDB reloads all extensions configured in Engine Parameters.

For Example

{
	"connect_args":{
	"preload_extensions":["iceberg","httpfs"]
	}
}

This causes problems in some extensions. In this case, Iceberg fails to load, causing the query to fail with the following error

(duckdb.duckdb.InvalidInputException) Invalid Input Error: Initialization function "iceberg_init" from file "/app/superset_home/.duckdb/extensions/v1.1.3/linux_amd64_gcc4/iceberg.duckdb_extension" threw an exception: "Table Function with name "iceberg_snapshots" already exists!" (Background on this error at: https://sqlalche.me/e/14/f405)

DuckDB Engine Version

0.17.0

DuckDB Version

1.1.3

SQLAlchemy Version

No response

Relevant log output

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