Able to switch off question recommendation

[wwwy3y3]

Is your feature request related to a problem? Please describe.
Question recommendation requires additional computation resources. Since this feature may not be needed in some scenarios, we could let users choose to disable.

Describe the solution you'd like
Bringing in a env variable that could turn off the question recommendation feature on following parts:

1. Home page: https://docs.getwren.ai/oss/guide/home/ask#recommended-questions
2. When questions require clarification: https://docs.getwren.ai/oss/guide/home/ask#out-of-scope-questions
3. When users question is a Database Schema Exploration: https://docs.getwren.ai/oss/guide/home/ask#database-schema-exploration
4. In follow-up questions: https://docs.getwren.ai/oss/guide/home/answer#recommended-questions

Additional context

1. also need an argument for the launcher to specify, ex: --diable-feature-recommendation