Grid clearable sort issue

[nebojsa-peric]

When we define Grid with clearableSort and defaultSortField, sorting by the field marked as the defaultSortField doesn't work.
The exact behavior also depends on the defaultSortDirection. If defaultSortDirection is set to DESC, clicking on the header, resets the sorting correctly, however, the defaultSortField sorts the grid again by the same field. So you stay infinitely in the DESC state. If defaultSortDirection is set to ASC, sorting keeps switching between ASC and DESC. So you can never go into a 'no-sort' state. This doesn't happen with other fields.