Refactor features and remove redundant ones

[brionmario]

Is your suggestion related to an experience ? Please describe.

1. There are few features that are still inside extensions after the unification.

• Administrators: [🧹 UNIFICATION CLEANUP] Move administrators from extensions to a dedicated feature -> @wso2is/admin.administrators.v1 identity-apps#6692

2. There are some unwanted features.

• @wso2is/admin.extensions.v2: https://github.com/wso2/identity-apps/tree/c636e89f61a035e82014bed2cccb904e79c15cf1/features/admin.extensions.v2

Describe the improvement

Need to move these inside features.

Additional context
N/A