Change DB SSL default to prefer from require

[VineethReddy02]

Is your feature request related to a problem? Please describe.

Today Promscale Connector by default uses the SSL auth as require. To improve the user experience for users who want to use allow or require make the default as prefer. The client negotiates the SSL auth with the DB.

Describe the solution you'd like.
Ease DB integration with Promscale connector. Also, Postgres default SSL mode is prefer.

Describe alternatives you've considered
Using only allow, but this would impact existing users to explicitly set it to require

How would this feature help you*
Easy onboarding with DB connection configuration.

Additional context
This has been discussed in joint sync-up and decided to use prefer as the default.