Fix schema_adapter integration tests not running (apache#16835)

- Removed `schema_adapter_integration_tests.rs` from the `integration_tests` directory.
- Created a new module `schema_adapter` and moved the tests there.
- Added `mod schema_adapter;` to `core_integration.rs` to include the new module.
- Enhanced the schema adapter test suite to:
  - Write and read test data using `InMemory` object store.
  - Validate consistent behavior of the `UppercaseAdapterFactory` across `ParquetSource`, `ArrowSource`, `CsvSource`, and `JsonSource`.
  - Confirm schema mapping behavior and adapter output schemas.
- Added missing `use` imports and corrected adapter error handling in existing test files.

Author: kosiew

datafusion/core/tests/core_integration.rs

@@ -45,6 +45,9 @@ mod optimizer;
 /// Run all tests that are found in the `physical_optimizer` directory
 mod physical_optimizer;
 
+/// Run all tests that are found in the `schema_adapter` directory
+mod schema_adapter;
+
 /// Run all tests that are found in the `serde` directory
 mod serde;