[Refactor] Update predicated global load/store lowering configuration
- Changed the configuration option from `kDisableLowerLDGSTGPredicated` to `kEnableLowerLDGSTGPredicated` to enable predicated lowering of global load/store operations.
- Updated relevant comments and documentation to reflect the new configuration behavior.
- Adjusted tests to utilize the new configuration option for enabling predicated lowering, ensuring consistency across the codebase.