[kernel-spark] Add failing tests for 17 DSv2 streaming feature-matrix bugs (V1+V2 parity)

[zikangh]

Which Delta project/connector is this regarding?

• Spark
• Standalone
• Flink
• Kernel
• Other (fill in here)

Description

Adds 11 test files (1 Scala helper + 10 Java) that reproduce 17 DSv2 streaming bugs catalogued in the DSv2 Streaming AI-assisted Feature Matrix Testing doc. Every test exercises both the DSv1 (spark.readStream().format(\"delta\").load(path)) and DSv2 (spark.readStream().table(\"dsv2.delta.\`")`) streaming paths and asserts they produce identical results (V1 as oracle), so each bug surfaces as a V1-vs-V2 divergence.

Bugs covered:

#	File	Bug
1	V2StreamingDeletionVectorVariantTest	DV reads silently corrupt VARIANT columns
2	V2StreamingReadTest (added 1 method)	NPE on partitioned tables when partition col isn't last
3, 7, 16, 17, 21	SparkGoldenTableTest (already differential)	Silent value swap / restart row-dup / projection+filter+rate-limit
4, 5, 6	V2PartitionValueBoundaryTest	Partition-value encoding boundaries
10	V2StreamingRowTrackingTest	AIOOBE projecting _metadata.row_id
11	V2StreamingIctTest + IctTestUtils.scala	ICT mid-history resolves startingTimestamp to v0
18, 19, 20	UCDeltaStreamingEdgeDataReadTest	UC MANAGED null-column NPE + empty-table precondition
23	V2StreamingRaceLifecycleTest	Long-running stream misses mid-stream protocol upgrade
24	V2StreamingMidPriorityScenarios13to18Test	maxBytesPerTrigger off-by-one (V1+V2 shared bug → asserts against oracle, not V1==V2)
25, 26	V2StreamingSchemaRejectionTest	VOID column unloadable; user-schema silently accepted

These tests are intended to fail on master — they exercise the bug, with V1 acting as the oracle. The fixes live on a separate stack and will land in follow-up PRs; this PR is the regression net.

How was this patch tested?

sparkV2/Test/compile, sparkUnityCatalog/Test/compile, sparkV2/Test/javafmtCheck, sparkUnityCatalog/Test/javafmtCheck all pass on Java 17. Tests themselves are expected to fail (intentional — V2 path broken; V1 is oracle).

Does this PR introduce any user-facing changes?

No.