Usage of Gluten Functions At Query Level

### Backend

VL (Velox)

### Bug description

Hello Team,

I am currently testing Gluten to benchmark its performance against TPCH. In the process, I observed that in TPCH Query 16, In Flame Graph we see only 4.69% of the function usage of the overall seems to be utilized.

I would like to understand if this utilization level aligns with our expectations. Additionally, could we confirm if this level of utilization contributes significantly to the execution speedup?

Attached is the Flame Graph we have generated.

### Spark version

None

### Spark configurations

_No response_

### System information

_No response_

### Relevant logs

_No response_