[FIX] Improve loader UX and abort race condition handling

[arturrybalskyy-dev]

[FIX] Fix loader UX and abort race condition handling across multiple pages

📝 Description

Fixes two related UX issues that appeared across several pages:

1. Loaders were covering ActionBar buttons and filters, making them inaccessible during data fetching
2. Rapid filter changes or refreshes caused stale data race conditions due to missing request cancellation

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🛠️ Changes Made

• Fix <Loader overlay /> placement in Artifacts, Models, ModelEndpoints, MonitoringApplications, and FeatureStore pages — loaders no longer cover ActionBar/filters
• Replace loading ? null pattern with <Loader section secondary /> to show visible loading state below ActionBar
• Add abort-before-new pattern (AbortController) to MonitoringApplicationsPage and ModelEndpointsTable to prevent stale data race conditions on rapid refresh/filter changes
• Wire AbortController signal via httpClient interceptor (requestLargeDataOnFulfill) so requests using config.ui.controller are properly canceled
• Fix NoData flash on aborted ModelEndpoints fetch by guarding fulfilled handler against undefined payload
• Extract shared isRequestAborted(message) utility to replace repeated inline [REQUEST_CANCELED, DEFAULT_ABORT_MSG].includes(...) checks across reducers and components

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✅ Checklist

• I have given the PR a well-structured title describing the domain and the specific change that was made
• I tested the changes in the browser (locally or via preview build)
• I confirmed that existing tests pass
• I added or updated unit / integration tests (if needed)
• I checked that this change doesn't introduce new console warnings or lint / formatting errors
• I updated the relevant Jira ticket with the appropriate details and status

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🔗 References

• Related ticket / issue:
• Figma / design spec:
• Documentation:

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🚨 Potentially Breaking Changes

• Yes
• No

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Includes DRC change

• Yes
• No