[v3-3-test] Pin lang-SDK k8s test's Go/Java SDKs to upstream main (#69545)

[github-actions]

• Pin lang-SDK k8s test's Go/Java SDKs to upstream main

Release/backport branches often lack go-sdk/java-sdk entirely or carry a
stale, branch-cut-frozen copy, so backporting a core/task-sdk fix to such
a branch would otherwise run the lang-SDK coordinator test against a
missing or outdated SDK snapshot. The Go bundle and Java jar builds now
always fetch go-sdk/java-sdk from upstream main regardless of the checked
out branch, while airflow-core/task-sdk and the test's own harness
fixtures keep tracking whatever branch is checked out.

Fix lang-SDK Java build missing task-sdk sibling in native mode

java-sdk's sdk/build.gradle.kts reads a sibling ../task-sdk/.../schema.json
at build time. The upstream-main extraction only contains go-sdk/java-sdk,
so building from it directly (native/CI toolchain mode) failed looking for
a task-sdk directory that doesn't exist. Symlink the real, local task-sdk
alongside the extraction so the reference resolves, without pulling
task-sdk itself from upstream.

Restore lang-SDK k8s test's gradle wrapper jar dropped by export-ignore

java-sdk/.gitattributes marks gradle/wrapper/gradle-wrapper.jar export-ignore
so ASF source-release tarballs stay free of compiled binaries (LEGAL-570).
git archive, used to pull go-sdk/java-sdk out of upstream main for this test,
respects that attribute and silently drops the jar, leaving the extracted
java-sdk's ./gradlew unable to find itself and failing every build.

Shorten gradle-wrapper.jar restoration comments

• Restore gradle wrapper scripts dropped by export-ignore in lang-SDK k8s test

Upstream main's java-sdk/.gitattributes export-ignores gradlew and
gradlew.bat (ASF LEGAL-570) in addition to the wrapper jar, so the
git-archive extraction of upstream sources no longer contains the
wrapper script the Java build invokes, failing CI with
FileNotFoundError: './gradlew'. Restore all three wrapper files from
the pinned commit instead of only the jar.

• Fix breeze k8s setup-lang-sdk-test crash with --dry-run

In dry-run mode run_command skips execution and returns stdout="" (a
str), so every filesystem step consuming a command's output crashed:
write_bytes on the gradle wrapper restore raised TypeError, the Go
bundle copytree/copy raised FileNotFoundError, the Java jar glob hit
sys.exit(1), and the artifact upload raised StopIteration. Guard those
steps so --dry-run prints the full provisioning command sequence and
completes cleanly.
(cherry picked from commit c22cc6d)

Co-authored-by: Jason(Zhe-You) Liu 68415893+jason810496@users.noreply.github.com

[vatsrahul1001]

@jason810496 docs check failing

[jason810496]

@jason810496 docs check failing

IIUC, other PR fixed it, I will merge this one.
Then backports of #70561 and #70824 should fix the Lang-SDK k8s test on v3-3-test.