[GLUTEN-12377][CI] Stop quarantining the Delta DV row-index failures

.github/workflows/util/delta-spark-ut/README.md

@@ -176,23 +176,32 @@ and blank lines allowed:
 ### Quarantine by error signature
 
 Some bugs surface on a **different test each run** — for example the native Delta
-DV bitmap row-index error (the aggregator gets a garbage row index during a MERGE
-that writes deletion vectors and aborts, e.g. `Delta RoaringBitmapArray row index
+DV bitmap row-index error (the aggregator got a garbage row index during a MERGE
+that writes deletion vectors and aborted, e.g. `Delta RoaringBitmapArray row index
 ... exceeds max representable value` or `Delta bitmap row index cannot be
-negative: ...`) lands on a different `*DVs*Suite` MERGE test every time. Chasing
+negative: ...`) landed on a different `*DVs*Suite` MERGE test every time. Chasing
 those by name is whack-a-mole, so quarantine them by **root cause** in
 **`flaky-error-patterns.txt`** instead: each line is a regex matched against a
 failed test's `<failure>`/`<error>` text. Any failure that matches is treated as
 flaky regardless of which test it hit (and is dropped from the shard's failures
 list so it can't leak into the baseline):
 
 ```
+# HISTORICAL EXAMPLE -- no longer active; flaky-error-patterns.txt has no
+# entries. Do not copy these back in: the bug they matched is fixed.
 # regex matched against the failure message + stack (enforce mode).
 # one explicit pattern per known error, deliberately specific.
 Delta RoaringBitmapArray row index \d+ exceeds max representable value
-Delta bitmap row index cannot be negative: -?\d+
+Delta bitmap row index cannot be negative: -\d+
 ```
 
+The root cause was a Velox scan bug
+([velox#18535](https://github.com/facebookincubator/velox/issues/18535)), fixed
+by [velox#18536](https://github.com/facebookincubator/velox/pull/18536) and
+picked up by the `dft-2026_08_21` Velox pin, so both patterns were removed and
+the suite is enforced again. The example is kept because it shows the shape of
+the mechanism.
+
 This is more precise than a name glob: a *different* real failure in the same
 suite is still caught, because only failures carrying the signature are ignored.
 

.github/workflows/util/delta-spark-ut/flaky-error-patterns.txt

@@ -10,37 +10,5 @@
 # surfaces on a different test each run, so matching by test name is
 # whack-a-mole. Prefer fixing the underlying bug and REMOVING the entry.
 #
-# ---------------------------------------------------------------------------
-# Native Delta bitmap aggregator receives an INVALID row index during a MERGE
-# that writes deletion vectors, and aborts. The garbage row index trips one of
-# two bounds checks, so the same root cause shows up with two messages:
-#
-#   too large (Long.MAX_VALUE):
-#     VeloxRuntimeError INVALID_STATE
-#     Reason: Delta RoaringBitmapArray row index 9223372036854775807 exceeds max
-#             representable value 9223372030412324864
-#     Expression: value <= kMaxRepresentableValue
-#     Function: addSafe  File: .../velox/compute/delta/RoaringBitmapArray.cpp:92
-#
-#   negative (garbage):
-#     VeloxRuntimeError INVALID_STATE
-#     Reason: Delta bitmap row index cannot be negative: -6254810385378525259
-#     Expression: value >= 0
-#     Function: addRowIndex  File: .../operators/functions/delta/DeltaBitmapAggregator.cc:44
-#
-# Both are the same root cause (garbage row index into the DV bitmap aggregator)
-# but distinct native errors, so each has its own explicit pattern below --
-# deliberately specific (bound to the exact error string) rather than a broad
-# "Delta bitmap row index" match, to avoid masking an unrelated failure. Add a
-# new line if a further bounds-check variant appears. Intermittent (depends on
-# the runtime plan/scan/scheduling), so it hits a different *DVs*Suite MERGE test
-# on each run. Remove these once the row-index materialization is fixed in the
-# native backend. Tracked upstream (DV bitmap invalid row index).
-# ---------------------------------------------------------------------------
-# too-large (Long.MAX_VALUE) -- RoaringBitmapArray.cpp addSafe, value <= kMaxRepresentableValue
-Delta RoaringBitmapArray row index \d+ exceeds max representable value
-# negative garbage -- DeltaBitmapAggregator.cc addRowIndex, value >= 0
-# The check is `value >= 0`, so the reported index is always negative: match the
-# sign explicitly rather than `-?` so this can't quarantine an unrelated failure
-# if the message format ever changes.
-Delta bitmap row index cannot be negative: -\d+
+# There are currently no quarantined error signatures. Add one below when a
+# nondeterministic bug starts landing on a different test each run.

.github/workflows/util/delta-spark-ut/flaky-tests.txt

@@ -18,7 +18,5 @@
 #
 # NOTE: when a bug surfaces on a DIFFERENT test each run (so matching by name is
 # whack-a-mole), quarantine it by ERROR SIGNATURE in flaky-error-patterns.txt
-# instead. The native Delta DV bitmap row-index bug (RoaringBitmapArray
-# Long.MAX_VALUE) is handled there, which is why no `*DVs*Suite` MERGE entries
-# are listed below.
+# instead.