[automation] update elastic stack version for testing 7.15.0-2cefb6a4#600

Merged

mergify[bot] merged 1 commit into7.xfrom update-stack-version-20210729051307-7.x

Jul 29, 2021

+1-1

Commits on Jul 29, 2021

[Automation] Update elastic stack version to 7.15.0-2cefb6a4 for testing
apmmachine
committed