Managing common functionalities of benchmark in a separate utils dir

### 🚀 Feature Description and Motivation

As we are likely to expand the benchmarks that we are going to support. This issue is to maintain common utils in a separate directory. Related files should be updated too. For example, `aibrix/benchmarks/autoscaling/run-test.sh`.

The future benchmarks should also use the `aibrix/benchmarks/utils`.

### Use Case

improving benchmark utils

### Proposed Solution

maintaining a separate utils dir for all benchmarks