DurationFormatter: Fix Digital Data SourceDataProvider

[kartva]

follow up to #5208

SourceDataProvider incorrectly generated the following padding data for h:mm:ss:

 "hms_padding": {
    "h": 1,
    "m": 1,
    "s": 1
  },

This was due to an oversight in using split_once which consumes the character used to split. From split_once documentation: assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));

Previous code incorrectly assumed the splitting character was not consumed.
This PR rectifies the error and regenerates testdata and bakeddata.