Correction of list of branches display 2 times in combobox

The list of branch is feed in InitToolStripBranchFilter() and also
in UpdateBranchFilterItems() but filtered if needed.
Remove first call to prevent displaying of branches twice that
happens due to an Async call...
Merge pull request #2324 from pmiossec/correct_list_branches

Correction of list of branches display 2 times in branches combobox