Fix Step Functions context injection

[avedmala]

What and why?

Closes https://github.com/DataDog/datadog-ci/issues/1429

How?

A brief description of implementation details of this PR.

Review checklist

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration)

[datadog-datadog-prod-us1[bot]]

Datadog Report

Branch report: avedmala/sfn-context-prop-fix Commit report: 011de77 Test service: datadog-ci-tests

:white_check_mark: 0 Failed, 1848 Passed, 0 Skipped, 1m 57.81s Total duration (1m 29.24s time saved)