Add integration tests for Pushed Authorization Requests (PAR) feature

[Yoshani]

Is your suggestion related to an experience ? Please describe.
The Pushed Authorization Requests (PAR) feature was introduced to product IS with PR [1]. Integration tests need to be added for the feature.

Related Issues

• Issue Support the OAuth2.0 PAR specification #9110
• Issue Improvements to PAR implementation #16013

Related PRs

• PR Add Pushed Authorization Request support for IS wso2-extensions/identity-inbound-auth-oauth#2050

[Yoshani]

Integration tests added with #16508