Fix PoolBar links using wrong query params for task instances page

[Karthikeya1500]

Clicking on a pool slot segment (e.g. running or queued) in the Pools page navigates to /task_instances but the state and pool filters don't get applied. The task instances page shows unfiltered results instead.

The root cause is that PoolBar.tsx uses SearchParamsKeys.STATE (state) and SearchParamsKeys.POOL (pool), but the TaskInstances page actually reads from SearchParamsKeys.TASK_STATE (task_state) and SearchParamsKeys.POOL_NAME_PATTERN (pool_name_pattern). The parameter name mismatch causes the filters to be silently ignored.

I also noticed slot.color was being used as the state value instead of slot.slotType. They happen to match for non-open slots right now, but slotType is the semantically correct value to pass as a task instance state filter.

- to={`/task_instances?${SearchParamsKeys.STATE}=${slot.color}&${SearchParamsKeys.POOL}=${pool.name}`}
+ to={`/task_instances?${SearchParamsKeys.TASK_STATE}=${slot.slotType}&${SearchParamsKeys.POOL_NAME_PATTERN}=${pool.name}`}

[boring-cyborg]

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