MarathonConstraintPrefix is the prefix for each label's key created from a Marathon application constraint.
It is used in order to create a specific and unique pattern for these labels.
Match reports whether the expression matches with the given labels.
The expression must match any logical boolean combination of:
- `Label(labelName, labelValue)`
- `LabelRegex(labelName, regexValue)`
- `MarathonConstraint(field:operator:value)`