[INTERNAL] sap.m.Tree: indentation calculation is corrected
[INTERNAL] sap.m.Tree: indentation calculation is corrected

Change-Id: I4a657bd7357f43c3a07d55e3da0c3f38cc82f9dd
BCP: 1880729416
Fixes: https://github.com/SAP/openui5/issues/2291
SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5