Fix: Handle partial consumer group lag calculation failures

[ngyngcphu]

Fixed #2573
Related to #2327

Before fix, run test TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure, got error:

go test ./pkg/console -run '^TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure$' -count=1 -timeout=3m -v                           ─╯

=== RUN   TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure
=== RUN   TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/listener_not_found
    consumer_group_offsets_test.go:296:
                Error Trace:    /Users/lap60627/Documents/PTO/console/backend/pkg/console/consumer_group_offsets_test.go:296
                Error:          Received unexpected error:
                                failed to list end offsets for topics: LISTENER_NOT_FOUND: There is no listener on the leader broker that matches the listener on which metadata request was processed.
                Test:           TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/listener_not_found
=== RUN   TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/leader_not_available
    consumer_group_offsets_test.go:296:
                Error Trace:    /Users/lap60627/Documents/PTO/console/backend/pkg/console/consumer_group_offsets_test.go:296
                Error:          Received unexpected error:
                                failed to list end offsets for topics: LEADER_NOT_AVAILABLE: There is no leader for this topic-partition as we are in the middle of a leadership election.
                Test:           TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/leader_not_available
--- FAIL: TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure (0.03s)
    --- FAIL: TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/listener_not_found (0.02s)
    --- FAIL: TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/leader_not_available (0.02s)
FAIL
FAIL    github.com/redpanda-data/console/backend/pkg/console    1.145s
FAIL

After fix, run test TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure successfully:

go test ./pkg/console -run '^TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure$' -count=1 -timeout=3m -v                           ─╯

=== RUN   TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure
=== RUN   TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/listener_not_found
=== RUN   TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/leader_not_available
--- PASS: TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure (0.04s)
    --- PASS: TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/listener_not_found (0.02s)
    --- PASS: TestGetConsumerGroupOffsets_PartialListEndOffsetsFailure/leader_not_available (0.02s)
PASS
ok      github.com/redpanda-data/console/backend/pkg/console    1.490s

[Copilot]

Pull request overview

This PR updates consumer group lag calculation to tolerate partial ListEndOffsets/ListOffsets failures (e.g., LISTENER_NOT_FOUND, LEADER_NOT_AVAILABLE) so the consumer group overview can still be returned for healthy partitions, aligning behavior with issues #2573 and #2327.

Changes:

• Treat kadm.ShardErrors from ListEndOffsets as non-fatal when some shards succeed, logging a warning and continuing with partial data.
• Populate per-partition error details when end offsets cannot be fetched, instead of failing the whole request.
• Add a regression test covering partial ListEndOffsets failures for common broker/partition error scenarios.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
backend/pkg/console/consumer_group_offsets.go	Allows consumer group lag calculations to proceed when end-offset fetches partially fail, surfacing failures per partition.
backend/pkg/console/consumer_group_offsets_test.go	Adds coverage for partial end-offset failures to ensure graceful degradation for consumer group lag results.

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