skill(apm-integrations): split tests.md into mandatory rules + situational style guide

[jordan-wong]

🤖 Generated with APM Instrumentation Toolkit

Reference / skill-fix PR. Two apm-integrations skill files; docs-only, no instrumentation code changes.

Splits tests.md so the rules every module needs aren't buried in the ones only some modules hit — restructuring alternative to #12359's inline trim, opened for comparison.

Changes

references/tests.md mixed always-applicable rules (DSL choice, error-test coverage, no-sleep hygiene) with situational rules and code examples that only apply to specific circumstances (version-mismatch comments, mutual-exclusion deps, latestDepTest source-set routing, banner-comment style) — 179 lines every reader loaded via SKILL.md Step 9.1's pointer, regardless of whether their module hit any of those cases.

• tests.md (28 lines) — the mandatory checklist only: DSL rule, error-test requirement, ForkedTest naming, integration-name registration, no-Thread.sleep()/no-default-jvmArgs hygiene.
• tests-style.md (148 lines, new) — situational rules + all code examples, linked from tests.md for the specific cases that need them.

Also folds in the DSL-rule clarification from #12359 (the old "Full Java instrumentation test support is not yet available" read as an absolute ban the repo's own Java-DSL test suites contradict).

Scope

references/tests.md, references/tests-style.md (new), SKILL.md — docs-only.

Alternative to #12359 — pick one; they overlap on the DSL-rule content.

[datadog-prod-us1-5]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 57.25% (-1.80%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 3a927df | Docs | View more details | Give us feedback!}

[dd-octo-sts]

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	14.01 s	14.00 s	[-0.8%; +0.8%] (no difference)
startup:insecure-bank:tracing:Agent	12.92 s	13.02 s	[-1.5%; +0.0%] (no difference)
startup:petclinic:appsec:Agent	17.50 s	17.28 s	[+0.2%; +2.3%] (maybe worse)
startup:petclinic:iast:Agent	17.50 s	17.59 s	[-1.3%; +0.3%] (no difference)
startup:petclinic:profiling:Agent	17.33 s	17.40 s	[-1.6%; +0.8%] (no difference)
startup:petclinic:sca:Agent	17.41 s	17.25 s	[-0.1%; +2.0%] (no difference)
startup:petclinic:tracing:Agent	16.52 s	16.57 s	[-1.4%; +0.7%] (no difference)

Commit: 3a927df5 · CI Pipeline · Benchmarking Platform UI

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