Skip discussions in the `issue_lock` workflow (#98146)
The last remaining `Lock Threads` failures are likely due to missing
permissions for discussions which `dessant/lock-threads` handles by
default.
This disables discussion handling to get the workflow green to start
tracking regressions. We can discuss if we want to lock inactive
discussions in a follow-up (which would be new behavior this workflow
never performed).
Co-authored-by: Claude Code (kimi-k3[1m]) <noreply@anthropic.com>
