[Features Platform] PHP schedule/basic fails when run against cloud

[dandavison]

See e.g. https://github.com/temporalio/features/actions/runs/12834770491/job/35792794659?pr=577

Running check Harness\Feature\Schedule\Basic\FeatureChecker::check FAILED

MarshallerException
Unable to unmarshal field `info` of class Temporal\Client\Schedule\Info\ScheduleListEntry
MarshallerException
Unable to unmarshal field `spec` of class Temporal\Client\Schedule\Info\ScheduleListInfo
MarshallerException
Unable to unmarshal field `jitter` of class Temporal\Client\Schedule\Spec\ScheduleSpec
InvalidArgumentException

Unrecognized date time interval format

cc @roxblnfk @rustatian

[roxblnfk]

I suppose we get null value in ScheduleSpec.jitter