Fix APM metric card calculations and clean up Services Home labels

[ps48]

Description

• Fix metric card calculations: Metric cards for fault rate, availability, and latency were showing inflated values (e.g., 575% fault rate) because showTotal mode summed all data points and divided by 1 instead of the number of data points. Fixed by defaulting the divisor to chartData.length when no explicit divisor is provided.
• Fix latency to use true percentile: Services Home latency column was showing the arithmetic mean of per-step P99 values. Added an instant query using sum_over_time on histogram buckets to compute the true P99/P90/P50 over the full selected time range.
• Fix throughput metric card: Removed misleading "Avg" subtitle and secondary raw count value from the throughput card — throughput (req/s) is a rate, not an average, and the raw count was confusing without context.
• Remove unused faultRate queries: getQueryAllOperationsFaultRate and getQueryAllDependenciesFaultRate were fetched but never rendered in the Operations or Dependencies tables. Removed to save 1 unnecessary Prometheus API call per tab.
• Label cleanup: Renamed "Avg. Latency" → "Latency", "Avg. throughput" → "Throughput" in Services Home. Updated tooltips to match current calculation logic.

Issues Resolved

#2545

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

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[ps48]

This is a known unused variable, will fix it in follow up PR later.