Count post-shutdown-dropped records as `already_shutdown` on processor.processed (#5509)

* Count post-shutdown-dropped records as processed with error.type=already_shutdown

Batch (span+log) and simple log processors previously dropped records
silently after shutdown. Count them on otel.sdk.processor.{span,log}.processed
with error.type=already_shutdown, matching the semantic conventions and the
.NET SDK. SimpleSpanProcessor is unchanged (it has no shutdown gate).

Assisted-by: Claude Opus 4.8

* Add changelog fragment for already_shutdown processed counting

Assisted-by: Claude Opus 4.8

* Fix lint: ruff-format wrap and too-many-lines disable

Assisted-by: Claude Opus 4.8

* Re-trigger CI

Signed-off-by: cijothomas <cijo.thomas@gmail.com>

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Signed-off-by: cijothomas <cijo.thomas@gmail.com>