Create PubSubIO Load test

[akashorabek]

This PR adds Load tests for PubSubIO. There are several configurations depending on the amount of data and the runner where the tests will be executed:

• local: Data volume is 0.2 MB. The test runs on the local machine using the Direct Runner.
• medium: Data volume is 10 GB. The test runs on the Dataflow runner.
• large: Data volume is 100 GB. The test runs on the Dataflow runner.

How to verify the results:

1. Install Gradle on your local machine.
2. Run the command gradle :it:google-cloud-platform:PubSubPerformanceTest --tests "org.apache.beam.it.gcp.pubsub.PubSubIOLT" -d from the project root to execute the tests.
3. The tests will pass successfully if all data is processed within a certain amount of time and the processed data matches the expected amount.
4. Additionally, upon running the test, a link for monitoring the job will be displayed in the terminal, providing more detailed information on how much data has been processed and the progress. An example link is: https://console.cloud.google.com/dataflow/jobs/us-central1/2024-02-13_00_10_16-5567586527775732420?project=apache-beam-testing.

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[akashorabek]

R: @damccorm @Abacn

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Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control

[akashorabek]

Thanks. Had a couple of initial comments. Is there a job id available for demonstration?

Here is the links to one of the tests: Write job: https://console.cloud.google.com/dataflow/jobs/us-central1/2024-02-21_02_10_37-12171205265624652554;step=Read%20from%20source;mainTab=JOB_GRAPH;bottomTab=JOB_ERROR_REPORTING;bottomStepTab=DATA_SAMPLING;logsSeverity=INFO;graphView=0?project=apache-beam-testing&pageState=(%22dfTime%22:(%22l%22:%22dfJobMaxTime%22)) Read job: https://console.cloud.google.com/dataflow/jobs/us-central1/2024-02-21_02_11_03-1874843895021090331;step=Read%20from%20PubSub;mainTab=JOB_GRAPH;bottomTab=DATA_SAMPLING;logsSeverity=INFO;graphView=0?project=apache-beam-testing