test: cover tablet map eviction on schema change (DRIVER-1000)

[nikagra]

TabletMapSchemaChangeListener had no unit test at all. TabletMapSchemaChangesIT mocks the listener out, so it proves the driver calls onKeyspaceDropped/onTableDropped but never that the listener forwards anything — the removeByKeyspace/removeByTable calls it makes were untested, as were its four no-tablet-map early returns.

• Covers all four listener callbacks, including onKeyspaceUpdated/onTableUpdated, which evict under the previous name — the cached tablets are keyed by it.
• Covers the early return on a server without tablets, so the callbacks are no-ops rather than an NPE.
• DefaultTabletMap: adds the second-sweep overlap eviction (a tablet overlapping only on its leading edge), removeByNode, and DefaultTablet's equals/hashCode/toString.
• Pins one behaviour worth knowing: removeByTable matches on table name alone, so dropping ks1.foo also evicts ks2.foo. The cost is a refetch, not mis-routing — recorded in a test comment, not filed as a defect.
• New cases use AssertJ, matching the rest of internal/core/metadata. The four existing methods in DefaultTabletMapTest mix JUnit with org.testng.Assert, whose assertEquals argument order is reversed; converting them is churn inside a coverage PR, so it is left alone deliberately.

Closes all 15 missed lines these two classes had in run 34559159215 (11 in DefaultTabletMap, 4 in the listener), plus the listener's 4 partial branches and DefaultTabletMap's L118/L135/L273. Reported as missed lines closed rather than a percentage, because the #1025 DSE-removal stack moves the aggregate ~3.7pp on its own.

Verified with mvn clean test -pl core: 3980 tests, 0 failures (3968 on the base branch + 12 new). Per-class coverage confirmed from jacoco.xml under -Pcoverage. No integration tests were run locally; the remaining parseTabletPayloadV1 partials are IT-covered in CI and were already partial at baseline.

Part of DRIVER-1000, one of five independent PRs off scylla-4.x — not a stack; this one shares no file with the others.

🤖 Generated with Claude Code

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