[CI] Add nightly system-tests workflow

[nccatoni]

Summary of changes

Adds a nightly workflow (system-tests-nightly.yml) that runs the official system-tests reusable workflow daily at 4 AM GMT.

Reason for change

Run system-tests regularly against the latest code on the default branch to catch regressions early.

Implementation details

Uses _system_tests_dev_mode so system-tests builds from source against the latest commit. Runs the tracer-release scenarios group and pushes results to Test Optimization. Follows the same pattern used in system-tests-dashboard nightly.

Test coverage

Trigger the workflow manually via workflow_dispatch and verify it completes successfully.

Other details

This is a CI-only change (new scheduled workflow), no code changes.

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-02-18 17:25:44

Comparing candidate commit db1676c in PR branch add-nightly-system-tests with baseline commit e0e1029 in branch master.

Found 11 performance improvements and 13 performance regressions! Performance is the same for 154 metrics, 14 unstable metrics.

scenario:Benchmarks.Trace.AgentWriterBenchmark.WriteAndFlushEnrichedTraces net6.0

• 🟥 execution_time [+81.794ms; +82.298ms] or [+67.971%; +68.389%]

scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleSimpleBody net6.0

• 🟩 execution_time [-19.420ms; -15.048ms] or [-8.860%; -6.866%]

scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleSimpleBody netcoreapp3.1

• 🟥 execution_time [+18.235ms; +22.364ms] or [+9.303%; +11.410%]

scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeLegacyArgs net6.0

• 🟩 execution_time [-27.478ms; -27.075ms] or [-13.501%; -13.303%]

scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeLegacyArgs netcoreapp3.1

• 🟥 execution_time [+28.297ms; +28.925ms] or [+16.130%; +16.488%]

scenario:Benchmarks.Trace.AspNetCoreBenchmark.SendRequest netcoreapp3.1

• 🟩 throughput [+519.386op/s; +1326.582op/s] or [+5.539%; +14.148%]

scenario:Benchmarks.Trace.CIVisibilityProtocolWriterBenchmark.WriteAndFlushEnrichedTraces net472

• 🟥 execution_time [+27.607ms; +33.351ms] or [+13.965%; +16.871%]
• 🟥 throughput [-84.180op/s; -56.722op/s] or [-7.997%; -5.389%]

scenario:Benchmarks.Trace.CIVisibilityProtocolWriterBenchmark.WriteAndFlushEnrichedTraces netcoreapp3.1

• 🟥 execution_time [+12.180ms; +18.685ms] or [+8.633%; +13.244%]

scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSlice net6.0

• 🟩 execution_time [-167.301µs; -161.552µs] or [-10.627%; -10.262%]
• 🟩 throughput [+72.759op/s; +75.416op/s] or [+11.454%; +11.872%]

scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearch net6.0

• 🟥 throughput [-46591.054op/s; -33120.160op/s] or [-7.256%; -5.158%]

scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearchAsync net472

• 🟥 throughput [-21201.923op/s; -18885.851op/s] or [-6.825%; -6.079%]

scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearchAsync net6.0

• 🟥 throughput [-43676.636op/s; -40877.916op/s] or [-7.127%; -6.670%]

scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearchAsync netcoreapp3.1

• 🟥 throughput [-56522.638op/s; -49516.946op/s] or [-11.932%; -10.453%]

scenario:Benchmarks.Trace.GraphQLBenchmark.ExecuteAsync net6.0

• 🟩 throughput [+31462.753op/s; +44461.043op/s] or [+6.071%; +8.580%]

scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatAspectBenchmark netcoreapp3.1

• 🟩 execution_time [-814.320µs; -702.823µs] or [-60.737%; -52.421%]

scenario:Benchmarks.Trace.RedisBenchmark.SendReceive net6.0

• 🟥 throughput [-78782.414op/s; -67050.917op/s] or [-13.981%; -11.899%]

scenario:Benchmarks.Trace.SerilogBenchmark.EnrichedLog net6.0

• 🟩 throughput [+12362.190op/s; +14701.029op/s] or [+5.510%; +6.552%]

scenario:Benchmarks.Trace.SingleSpanAspNetCoreBenchmark.SingleSpanAspNetCore net6.0

• 🟩 execution_time [-100.747ms; -98.759ms] or [-51.009%; -50.002%]

scenario:Benchmarks.Trace.SpanBenchmark.StartFinishScope netcoreapp3.1

• 🟩 throughput [+46309.837op/s; +70811.171op/s] or [+5.504%; +8.417%]

scenario:Benchmarks.Trace.SpanBenchmark.StartFinishSpan netcoreapp3.1

• 🟩 execution_time [-18.530ms; -12.994ms] or [-8.622%; -6.046%]

scenario:Benchmarks.Trace.SpanBenchmark.StartFinishTwoScopes netcoreapp3.1

• 🟥 execution_time [+10.321ms; +15.794ms] or [+5.242%; +8.022%]

scenario:Benchmarks.Trace.TraceAnnotationsBenchmark.RunOnMethodBegin net6.0

• 🟥 execution_time [+13.501ms; +19.177ms] or [+6.728%; +9.557%]