fix: network error and incorrect backend response for operations

[astandrik]

Closes #2488

CI Results

Test Status: ⚠️ FLAKY

📊 Full Report

Total	Passed	Failed	Flaky	Skipped
354	348	0	1	5

Test Changes Summary ✨3 ⏭️3

✨ New Tests (3)

1. shows error state when operations request returns network error (tenant/diagnostics/tabs/operations.test.ts)
2. handles malformed response without operations array (tenant/diagnostics/tabs/operations.test.ts)
3. stops pagination when receiving malformed response after valid data (tenant/diagnostics/tabs/operations.test.ts)

⏭️ Skipped Tests (3)

1. Query tab first row has values for all columns in Top mode (tenant/diagnostics/tabs/queries.test.ts)
2. Scroll to row, get shareable link, navigate to URL and verify row is scrolled into view (tenant/diagnostics/tabs/queries.test.ts)
3. TopShards tab first row has values for all columns in History mode (tenant/diagnostics/tabs/topShards.test.ts)

Bundle Size: ✅

Current: 84.00 MB | Main: 84.00 MB
Diff: +0.61 KB (0.00%)

✅ Bundle size unchanged.

ℹ️ CI Information

• Test recordings for failed tests are available in the full report.
• Bundle size is measured for the entire 'dist' directory.
• 📊 indicates links to detailed reports.
• 🔺 indicates increase, 🔽 decrease, and ✅ no change in bundle size.