[BUG] Proxy setting not work in Azure AD B2C web application

[chenrujun]

Context

1. [BUG] Make sure all RestTemplate are managed by AadRestTemplateCreator #31347
2. In Azure AD B2C web application, RestTemplate send the 2 http requests, both of them not supporting proxy setting.

https://rujche220928.b2clogin.com/rujche220928.onmicrosoft.com/oauth2/v2.0/token?p=B2C_1_sign_in_sing_up
https://rujche220928.b2clogin.com/rujche220928.onmicrosoft.com/discovery/v2.0/keys?p=B2C_1_sign_in_sing_up

Goal

Make sure all http requests send out by RestTemplate in Azure AD B2C web application supporting configure Proxy.