[SPARK-57694][INFRA] Upgrade test-summary/action to v2.6

[sarutak]

What changes were proposed in this pull request?

This PR upgrades test-summary/action from v2.4 (31493c76ec9e7aa675f1585d3ed6f1da69269a86) to v2.6 (37b508cfee6d4d080eedd00b5bb240a6a784a6a5).

The following link shows changes after v2.4.
test-summary/action@v2.4...v2.6

Why are the changes needed?

v2.6 includes Node.js 24 support. Node.js 20 is already EOL and deprecated in GA.
https://github.com/apache/spark/actions/runs/28157559069

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: test-summary/action@31493c76ec9e7aa675f1585d3ed6f1da69269a86. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Does this PR introduce any user-facing change?

No.

How was this patch tested?

GA.

Was this patch authored or co-authored using generative AI tooling?

No.

[uros-b]

Is this upgrade is complete? test-summary/action is used in five jobs in build_and_test.yml, all on the old v2 pin. The PR only updates the one in the build job. The other four are untouched:

• pyspark | still 31493c76 # v2
• sparkr | still 31493c76 # v2
• tpcds-1g | still 31493c76 # v2
• docker-integration-tests | still 31493c76 # v2

[uros-b]

Please make sure to update all five test-summary/action usages, not just the build job.

[uros-b]

In addition to an incomplete edit, I think that the SHA is wrong.

https://github.com/test-summary/action/releases/tag/v2.6:
test-summary/action@37b508c

Whereas the PR seems to be using 14d976eb4e1453d4890c48d781cf44b1cf67bbad.

[HyukjinKwon]

0 blocking, 0 non-blocking, 0 nits.
Correct and complete pinned-action bump.

Verification

Confirmed the pinned SHA 37b508cfee6d4d080eedd00b5bb240a6a784a6a5 is exactly what test-summary/action's v2.6 tag points to (lightweight tag → that commit), and that all five test-summary/action@ call sites in build_and_test.yml (lines 456/871/980/1588/1682) are updated — none left on the old v2.4 SHA. This resolves the earlier "is this upgrade complete?" comment (accurate on a prior commit; all five are now updated).