GlobalOffHeapMemory uses storage memory instead of execution memory

### Backend

VL (Velox)

### Bug description

GlobalOffHeapMemory uses storage memory instead of execution memory. Since it is used by plan validation and UnsafeColumnarBuildSideRelation, shouldn't it use execution memory? Is it intentional or a bug?

### Gluten version

_No response_

### Spark version

None

### Spark configurations

_No response_

### System information

_No response_

### Relevant logs

```bash

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Start by locating GlobalOffHeapMemory and tracing its callers in plan validation and UnsafeColumnarBuildSideRelation; compare how those paths use storage and execution memory. Resolve whether the current choice is intentional or a bug, then add or update focused coverage for the resulting behavior.

Written by the indexing model from the issue text.