TF_BUILD Set to True if the script is being run by a build task.
This variable is agent-scoped, and can be used as an environment variable in a script and as a parameter in a build task, but not as part of the build number or as a version control tag.
See: https://learn.microsoft.com/en-us/azure/devops/pipelines/build/variables?view=azure-devops&tabs=yaml