etcd: Improving KV Range Tests with Key Ascending and Limit

Problem

KV range tests lacked coverage for key ascending ordering and limit parameter combinations. These scenarios are critical for applications that paginate through large keyspaces.

Solution

Added unit tests covering:

• Key ascending ordering with various range boundaries
• Limit parameter behavior with different cursor positions
• Edge cases with empty results and boundary conditions

Result

Improved test coverage for etcd's KV range operations, ensuring reliable behavior across different query patterns.

Commit: etcd-io/etcd@cc03bc4