Projects: Update to LCG_101_ATLAS_10 and remove extra GDB configuration
This MR updates all projects to layer LCG_101_ATLAS_10 which comes with generators updates as discussed in https://sft.its.cern.ch/jira/browse/SPI-2052.
In addition it reverts MR !49520 (merged) that included an updated GDB configuration. This update is now also available via atlasexternals in MR !49561 (merged)