Monteverdi: fix band numbering in color setup widget

Band numbers start at 1. The convention is established by QGIS, GDAL, Sentinel-2, MODIS, LANDSAT, etc. Monteverdi displays the band name if it exists from the metadata, otherwise an index that starts at 1.

Fix this confusing widget in Monteverdi:

added bug label

I would like to request backport to release-6.6 as well

changed the description

merged

mentioned in commit af9f0099

mentioned in issue #1722 (closed)

mentioned in commit bd40ee18

changed milestone to %7.0.0