update response handling for false

[cykolln]

Description

This PR fixes behavior for when curl_exec returns something that is not explicitly false but evaluates to false (ex: null). This will prevent successful responses from retrying and follows the recommendation here: https://www.php.net/manual/en/function.curl-exec.php#refsect1-function.curl-exec-returnvalues

Manual Testing Steps

Pre-Submission Checklist:

• You've updated the CHANGELOG following the steps here
• Internal Only - If this is a release, please confirm the following:
  • The links in the changelog have been updated to point towards the new versions
  • The version has been incremented in the following places: module.xml and composer.json

NOTE: Please use the Changelogger cli tool to manage versioned file upgrades.