Issue #8758 : Do not mark loaded run configurations as changed

[mattcasters]

Opening a project restores the metadata tabs from the last session. Selecting a pipeline or workflow run configuration refreshes its metadata combos (the execution information location, and the data profile on a pipeline). On Windows that refresh notifies Modify even when the selected value did not change, so the editors mark the tab as changed.

MetaSelectionLine.fillItems() now leaves the combo alone when the list and the text are unchanged, and detaches modify and selection listeners while it rebuilds the list.

fixes #8758

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