[BUG] Disconnect the GitHub Account from Github Pipeline Preview Feature

## Bug Description

I was experimenting with the AKS Desktop GitHub Pipeline feature; I enabled it via the settings and did the initial configuration. For me the configuration didn't work as expected, so I was trying to do the GitHub configuration from the beginning.

I disabled the feature from the settings, and then I created a new AKS automatic cluster and tried to set up the GitHub pipeline. Still I do see my username is connected and I dont see an option to disconnect the GitHub account

I think there should be an option or setting to disconnect from the GitHub account and configure it from the beginning. when it needed

## Environment

- **Plugin Version**: 0.9.1

Start by reproducing the GitHub Pipeline configuration from the settings and an AKS automatic cluster, including disabling and re-enabling the feature. Trace where the connected GitHub username remains visible and verify that users can disconnect the account and configure the pipeline again from the beginning.

Written by the indexing model from the issue text.