Fix workflow query timeout client reuse

[rmcdaniel]

Closes #8.

Summary

• use a fresh short-timeout client for the cluster-info probe so the real workflow query request can build its own longer-timeout client
• keep the shared cached client path for the actual command execution instead of poisoning it with the 5-second probe client
• update the regression test to exercise the real cached-client path that failed in production

Validation

• composer install --no-interaction --prefer-dist
• php ./vendor/bin/phpunit tests/Commands/WorkflowHistoryQueryTest.php tests/Commands/MutatingCommandJsonTest.php
• manual JSON workflow query smoke against a local Durable Workflow server