Add Jitter in event poll delay at the beginning of Elastic Beanstalk Deploy Tasks

[jeremyjpaws]

Is your feature request related to a problem? Please describe.

Feature request related to internal ticket #IDE-1782

Issue is that deployments to many AWS Elastic Beanstalk environments at the same time can hit high throttles on DescribeEnvironment API calls. This is due to the shared default 5 second value of the Event poll delay setting. This can cause a pipeline to fail execution when describing deployment status are unable to query status due to throttles.

Describe the solution you'd like

The best solution would be some default jitter applied behind the scenes to the Event poll delay value. However setting this setting every time requires a bit of effort, and is subject to human error.

Describe alternatives you've considered

A working alternative is to manually vary the Event poll delay setting for each deploy task in the pipeline.

** Additional comments **

This issue appears potentially similar to https://github.com/aws/aws-vsts-tools/issues/62 and might share the same root cause, therefore this feature would solve a few open issues relating to throttles.