Update Caffeine to 3.2.4, Checkstyle to 10.26.1 and audience-annotations to 0.15.1

[porunov]

Follow-up to #4948 / #3547: the dependency updates that were blocked on Java 8 support.

Dependency	Before	After	Notes
com.github.ben-manes.caffeine:caffeine	2.9.3	3.2.4	Caffeine 3 requires Java 11
com.google.errorprone:error_prone_annotations (managed)	2.30.0	2.50.0	required by Caffeine 3.2.4 (requireUpperBoundDeps)
com.puppycrawl.tools:checkstyle	9.3	10.26.1	last Checkstyle line that runs on Java 11
maven-checkstyle-plugin	3.4.0	3.6.0
org.apache.yetus:audience-annotations (managed)	0.13.0	0.15.1	transitive of hbase-shaded-client

Caffeine 3

JanusGraph's seven Caffeine call sites (ExpirationKCVSCache, CaffeineVertexCache, CaffeineSubqueryCache, RelationQueryCache, StandardSchemaCache, StandardLockCleanerService, StandardTransactionLogProcessor) only use builder options and Cache methods that are unchanged in 3.x; none of the APIs removed in 3.0 (CacheWriter, StatsCounter.recordEviction variants, CacheStats constructors, UnsafeAccess) are used. Caffeine 3.2 switched its nullness annotations from the Checker Framework to JSpecify, so the checker-qual exclusion on the janusgraph-core dependency no longer excluded anything and is removed; the managed error_prone_annotations is raised to the version Caffeine 3.2.4 declares.

Checkstyle 10

Checkstyle 11 and newer require Java 17, so 10.26.1 is the ceiling while JanusGraph builds on Java 11. The inline rule set in the root POM works unchanged and reports 0 violations in all 32 modules (main and test sources).

Verification

• mvn install -DskipTests on Java 11: enforcer (requireUpperBoundDeps) and Checkstyle pass on every module.
• Test suites run locally with the new versions: janusgraph-core (82 tests), janusgraph-inmemory (572, exercises the Caffeine-based vertex, subquery, schema and KCVS caches through JanusGraphTest) and janusgraph-test (998) on Java 11, plus janusgraph-core and janusgraph-inmemory on Java 25 — all green.

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