function isLegacyAwsBehavior(locationConstraint) {
    return (config.locationConstraints[locationConstraint] &&
      config.locationConstraints[locationConstraint].legacyAwsBehavior);
}
check the legacy AWS behaviour
For new configuration: check if locationConstraint has its
legacyAwsBehavior put to true
@param {string | undefined} locationConstraint - value of user
metadata location constraint header or bucket location constraint
@return {boolean} - true if valid, false if not