skip_intermediate_results now works in parallel merge queue mode

When skip_intermediate_results is enabled, Mergify merges a pull request as soon as a later batch that includes it passes its checks, instead of waiting for the PR’s own speculative check. Previously available only in serial mode, it now applies in parallel mode too — within each scope’s dependency chain, a passing batch promotes its not-yet-merged ancestors so busy scopes get the same speedup serial queues already enjoy.