[BUG] `./gradlew run` task is broken for plugins

Describe the bug The ./gradlew run task allows plugin developers to launch a test cluster with the plugin pre-installed. This allows for quick development and testing cycles. This worked fine until 7.9 but has been broken since 7.10, and therefore in OpenSearch.

Plugin developers end up having to manually configure the 'run' task in their build.gradle file to launch a test cluster with the required plugins (and extended plugins) pre-installed.

Issues

1. The 'run' task doesn't launch a test cluster.
2. The test cluster launched by the 'integTest' task doesn't have the plugin pre-installed.

To Reproduce

1. Create a simple OpenSearch plugin. For convenience, clone this OpenSearch plugin template - https://github.com/ketanv3/opensearch-plugin-boilerplate
2. In the project's root directory, run ./gradlew run.
3. Gradle will be stuck at the :run task but no cluster will be launched.

Expected behavior A test cluster should be launched with the plugin (and extended plugins) pre-installed.

1. A new test cluster should be created and registered for the 'run' task.
2. For the test clusters launched by 'run' and 'integTest' tasks, pre-install the bundled plugin ZIP.

Host/Environment

• OS: Tested on macOS 11.2.3, Ubuntu 20.04.2 LTS
• Version: 1.0.0-rc1