UUID Handling Fix, 1.0 branch (2020.09.29.)

This is a follow-up from !734 (merged).

Unfortunately while that MR made sure that all clients would pick up uuid consistently from LCG_88 (and LCG_88b) on the x86_64-centos7-gcc62-opt platform, I didn't realise at that point that the TDAQ projects did not pick up UUID from the LCG release. The TDAQ releases were built against the OS's UUID library.

This meant that while !734 (merged) fixed the issue described in ATLINFR-3736, it also introduced another, new issue. A build failure in ByteStreamCnvSvc in a number of projects. 😦 Thanks to @boeriu for bringing this to my attention!

I decided not to ditch LCG's UUID library completely however. Since we can now consistently pick it up for all of the offline projects from the LCG release if we want to, I would continue doing that for all the projects that do not use TDAQ releases. Instead I only force AthenaExternals and AthDerivationExternals to pick up UUID from /usr for everything. With this, I'm once again able to build all of AthDerivation-21.2 successfully for x86_64-centos7-gcc62-opt.