./backend.ai test run-cli command returns exit code 0 even on failure

[why-arong]

What Operating System(s) are you seeing this problem on?

Linux (x86-64)

Backend.AI version

24.09

Describe the bug

While investigating why our integration tests in a GitHub Action workflow were not failing as expected,
I discovered that the ./backend.ai test run-cli command returns an exit code of 0 even when it encounters a failure.

This behavior is misleading because it causes CI/CD pipelines to treat failing tests as successful, leading to false positives.

To Reproduce

1. Run the ./backend.ai test run-cli admin
2. Check the exit code immediately after the command finishes using echo $?

Expected Behavior

The command should return a non-zero exit code if it encounters any errors during execution.

Anything else?

No response