Detect CI Environment variables when collecting metrics

[robinjhuang]

Would be nice to detect CI environments and include that as a flag in metrics that are collected to avoid counting CI environments in the target metric.

CI:
Many CI systems set this to "true" or "1"
CI_NAME:
Identifies the specific CI system (e.g., "travis-ci", "circleci")
TRAVIS:
Set to "true" in Travis CI environments
CIRCLECI:
Set to "true" in CircleCI environments
JENKINS_URL:
Present in Jenkins environments
GITLAB_CI:
Set in GitLab CI environments
GITHUB_ACTIONS:
Set to "true" in GitHub Actions environments
BITBUCKET_COMMIT:
Present in Bitbucket Pipelines
TEAMCITY_VERSION:
Present in TeamCity environments
APPVEYOR:
Set to "True" in AppVeyor environments
DRONE:
Set to "true" in Drone CI environments
BUILD_NUMBER or BUILD_ID:
Often set in various CI systems