SAMZA-2796: Introduce config knob for framework thread sub DAG execution

[mynameborat]

Description
As part of SAMZA-2781, we use framework thread pool to execute hand-offs and sub-DAG execution. We want to add a config knob to enable users opt-in to the feature as opposed to enable it by default.

Changes

• Introduce config knob to use the framework executor

Tests

• Added unit tests

API Changes
None

Usage Instructions
Refer to the configuration documentation. To enable framework thread pool for sub-DAG execution and message hand off, set job.operator.framework.executor.enabled to true

Upgrade Instructions
None

[alnzng]

LGTM. Thanks for providing a way to allow the users to have a way to keep the feature parity with previous versions.