Ecs provider fix

[dariussantaras]

Description

Fixes #2055

• The ECS 'describe tasks' SDK call now specifies the cluster explicitly.
• ECS monitoring poll interval is now correctly converted into seconds.

Purpose

This pull request is a:

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[CLAassistant]

All committers have signed the CLA.