Drop the stale animal-sniffer Java 1.7 API check from persistit

[vharseko]

Problem

master is red: run 29520187688. Every matrix job fails, on all OSes and JDKs.

The tests are fine — all 569 persistit tests pass. The build is failing on animal-sniffer:

[ERROR] Failed to execute goal org.codehaus.mojo:animal-sniffer-maven-plugin:1.20:check
        (enforce-java-api-compatibility) on project core: Signature errors found.

persistit/pom.xml pinned the signature to org.codehaus.mojo.signature:java17:1.0 — the Java 1.7 API surface — while four references to Java 8 APIs now exist in persistit/core:

Location	Reference
com/persistit/Key.java:519-520	ThreadLocal.withInitial(Supplier) + lambda → java.util.function.Supplier
com/persistit/BufferPool.java:1364	Long.hashCode(long) (×2)
com/persistit/JournalManager.java:2192	Long.hashCode(long)

Why it surfaced only now

Three independent things lined up, and the commit the build broke on is not the cause:

1. Run integration tests in the default CI build #270 switched CI from mvn package to mvn verify. animal-sniffer binds to the verify phase, so it had never run in CI before that — there is not a single animal-sniffer line in the logs of earlier builds.
2. Declare equals/hashCode consistent with compareTo (CodeQL java/inconsistent-compareto-and-equals) #232 (Long.hashCode) merged with green checks, but those checks had run days earlier under mvn package and were never re-run after Run integration tests in the default CI build #270 landed.
3. Make the shared Key.SDF date formatter thread-safe (CodeQL java/thread-unsafe-dateformat) #228 (ThreadLocal.withInitial) merged with build-maven red on all 9 jobs; its final run already showed exactly this animal-sniffer error.

The intermediate master runs were all cancelled by concurrency: cancel-in-progress as the PRs merged seconds apart, so the first master run to reach completion is the one that reported the failure.

Fix

The signature config was stale, inherited from the upstream Akiban Persistit build. The repository compiles at maven.compiler.release=11 (pom.xml), so the check was enforcing a baseline three releases below the declared one. Since JDK 9, release=11 makes javac reject newer APIs natively — which is precisely the job animal-sniffer existed to do before release was available. The check was both redundant and wrong, so this removes it rather than bumping the signature to a value that would still be below the real baseline.

Removed: the plugin declarations in the core and ui modules and the signature properties in the persistit parent. Nothing else refers to it — there are no @IgnoreJRERequirement annotations in the tree.

Verification

Reproduced and fixed locally under JDK 11 (matching the macos-latest, 11 job), mvn -pl persistit/core -am verify:

• before — BUILD FAILURE, same four Undefined reference errors as CI
• after — BUILD SUCCESS, and the goal no longer runs

Full verify across persistit/core + persistit/ui passes.