Refactor cutStart & cutEnd because of code duplication

[SergeyPodgornyy]

Detailed description

Code duplication, should be refactored

Context

To improve code quality

Possible implementation

Create another method to fix

Environment

see https://scrutinizer-ci.com/g/larapulse/support/inspections/99abc104-deaf-4494-90ee-55710454f5d7/issues/files/src/Handlers/Str.php?status=new&selectedLabels%5B0%5D=4&orderField=path&order=asc&fileId=src%2FHandlers%2FStr.php&honorSelectedPaths=0&issueId=25564280#inspectioncomment-92892212