Add network links for services containers in user-defined networks

What does this MR do?

• Adds network links for services container in user-defined network.
• Reads the service container's configuration for exposed ports.
• Uses explicit environment variables to configure the wait-for-service container instead of relying on Docker's deprecated link environment variables.

Why was this MR needed?

This solves the problem described in #2699 (closed).

Are there points in the code the reviewer needs to double check?

Does this MR meet the acceptance criteria?

• Documentation created/updated (no update needed)
• Tests
  • Added for this feature/bug
  • All builds are passing
• Branch has no merge conflicts with master

What are the relevant issue numbers?

#2699 (closed)