Externals and AthDerivation Updates, 21.2 branch (2020.09.29.)

This is to update all projects to atlasexternals-1.0.71. Which brings in one (type of) update wrt. atlasexternals-1.0.70 (atlasexternals@1.0.70...1.0.71): It makes AthDerivationExternals not use uuid from LCG_88.

Since while the previous update (!36689 (merged)) made all of the "offline" code use uuid all across the board from LCG_88, it turns out that the TDAQ projects are not doing that. They pick up UUID from the operating system... Which lead to a build error in ByteStreamCnvSvc in AthDerivation. 😦 (Thanks to @boeriu for making me aware of this!)

While doing this update, I also noticed that while AthDerivation started depending on YODA some time ago, it never "fixed" which version of YODA should be used. And hence it was not (easily) possible to build package(s) using YODA on top of the AthDerivation release/nightly. This MR should fix that issue as well.