[Fix] Stages to Run couldn't be selected (#18310)
### Description
Add the pool definition in 2 stages even the pool is Microsoft-Hosted
Pool.
### Motivation and Context
Recently, in Nuget pipeline, when we click the Stages to Run
It always pops up
```
Encountered error(s) while parsing pipeline YAML:
Could not find a pool with ID 5206. The pool does not exist or has not been authorized for use. For authorization details, refer to https://aka.ms/yamlauthz.
Could not find a pool with ID 5206. The pool does not exist or has not been authorized for use. For authorization details, refer to https://aka.ms/yamlauthz.
```
