UI: Update PoolBar to separate Scheduled and Deferred slots

[anshuksi282-ksolves]

Description

This PR addresses issue #53826.

Currently, the Pool Bar visually includes Scheduled and Deferred states inside the progress bar. This can be misleading as these states do not typically consume open pool slots, making the pool look "fuller" than it actually is.

Changes introduced:

1. PoolBar.tsx: Updated the filter logic to only display active slots (Running, Queued, Open) inside the visual bar.
2. PoolBarCard.tsx: Added logic to display Scheduled and Deferred counts as text/icons below the bar on the Pools administration page.
3. PoolSummary.tsx: Applied the same text display logic to the Dashboard "Pool Slots" widget for consistency.

Screenshots

Before:

After:

Related Issue

Closes #53826

---

^ Add meaningful description above Read the Pull Request Guidelines for more information. In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed. In case of a new dependency, check compliance with the ASF 3rd Party License Policy. In case of backwards incompatible changes please leave a note in a newsfragment file, named {pr_number}.significant.rst or {issue_number}.significant.rst, in airflow-core/newsfragments.