[Fix][CI] Increase all-connectors-it-5 timeout

[davidzollo]

Purpose

The all-connectors-it-5 GitHub Actions job repeatedly hit the configured 180-minute job timeout while checking PR #10780.

Observed evidence from run 24603834085 attempt 3:

• Run / all-connectors-it-5 (11, ubuntu-latest) started at 2026-04-19T05:03:51Z and was cancelled at 2026-04-19T08:04:06Z.
• Run / all-connectors-it-5 (8, ubuntu-latest) started at 2026-04-19T05:03:51Z and was cancelled at 2026-04-19T08:04:06Z.
• The cancelled step in both jobs was run connector-v2 integration test (part-5).

This connector group contains heavy modules such as ClickHouse, Elasticsearch, Iceberg S3, MaxCompute, Postgres CDC, SLS, and HugeGraph. The timeout is unrelated to the DB2 CDC/JDBC changes in #10780.

Changes

• Increase all-connectors-it-5 timeout from 180 minutes to 270 minutes.
• Keep it consistent with the existing heavy all-connectors-it-4 job timeout.

Tests

• ./mvnw spotless:apply -nsu -Dmaven.gitcommitid.skip=true -T 3C
• git diff --check
• ./mvnw -q -DskipTests verify -nsu -Dmaven.gitcommitid.skip=true -T 3C

[heye1005]

LGTM. Aligning with it-4's 270min makes sense given the heavy modules in this group.
and a minor thought for later: if this group keeps growing, might split it rather than increase timeout again.

[DanielLeens]

Hi @davidzollo, I pulled this PR locally as seatunnel-review-10788 and checked the workflow-only diff.

Runtime path affected:

GitHub Actions backend.yml
  -> all-connectors-it-5 matrix job
      -> timeout-minutes changes from 180 to 270
      -> no SeaTunnel runtime/source code path is changed

The change is intentionally narrow and matches the existing heavier connector IT groups. I do not see a source-code blocker in the diff itself.

Conclusion: can merge after fixes

Blocking item:

1. The PR should not merge while the latest Build check is CANCELLED. Please rerun the workflow and make sure the longer timeout actually produces a green run.

Once CI is green, this looks fine to me as a CI-only adjustment.