Support multi-arch connector image release

[shibd]

Fixes https://github.com/streamnative/product-roadmap/issues/1572

Summary

• Upgrade the connector runtime to Pulsar 4.2.0.6 and align shared dependency versions with Pulsar branch-4.2 where applicable.
• Update release image workflows to use Buildx/QEMU and publish linux/amd64,linux/arm64 images.
• Keep existing test boundaries unchanged; this PR does not add Surefire test excludes or change unit-test workflow commands.

Validation

• mvn clean install -DskipTests
• workflow YAML parse check
• git diff --check

Note: after keeping the original test boundaries, mvn test -Dtest="*Test" -DfailIfNoTests=false may reach existing external integration tests in some connectors and requires their normal external services, such as Docker/Testcontainers or LocalStack.

[github-actions]

@shibd:Thanks for your contribution. For this PR, do we need to update docs?
(The PR template contains info about doc, which helps others know more about the changes. Can you provide doc-related info in this and future PR descriptions? Thanks)