v3: remove all deprecated connection methods and their implementations

[bigbes]

Several methods in the core package have been marked as deprecated in previous releases and are no longer used in production code or examples. To reduce maintenance overhead, improve API clarity, and avoid confusion for new users, we should fully remove these deprecated methods—including their implementations, interfaces, and associated test cases.

Affected Files

• go-tarantool/request.go
• go-tarantool/connector.go

What to Remove

1. Identify all methods annotated with // Deprecated: in the above files.
2. Remove the method declarations from interfaces.
3. Delete the method implementations.
4. Remove any internal helpers or fields that are only used by these deprecated methods.
5. Update all tests** in pool/ that exercise the deprecated functionality—either delete the test cases or refactor them to use the current API.

Do not just comment out or disable the code — delete it completely. The goal is a clean, minimal, and forward-looking API.