Consolidate schema adapter tests in schema_adapter_integration_tests.rs

[kosiew]

Follow up task from #16148 (comment)

Move the tests in
datafusion/core/tests/test_adapter_updated.rs
to
datafusion/core/tests/integration_tests/schema_adapter_integration_tests.rs

[alamb]

Thanks @kosiew -- here is a PR:

• Simplify FileSource / SchemaAdapterFactory API #16214