Merge 21.0.118 into 21.3

This merge request merges all the changes that were made to the 21.0 branch between the release release/21.0.118 and the previous release release/21.0.117.

Below is the full list of merge requests that were included between these two tags:

• !36624 (merged) : Externals Update, 21.0 branch (2020.09.22.)
• !36642 (merged) : Sweeping !36565 (merged) from master to 21.0.
• !36597 (merged) : Sweeping !36550 (merged) from 21.2 to 21.0.
• !36600 (merged) : preInclude file of fractionally charged particles
• !36563 (merged) : Add overrides for HEC in overlay HI production
• !36363 (merged) : Fix running trigger int 21.0 with 22.0 RDOs
• !36401 (merged) : AFP webdisplay [rel 21]
• !36345 (merged) : Address path resolver issue in ATLASSIM-4674 and store ParamFile in HITS file metadata
• !36533 (merged) : Sweeping !36482 (merged) from 21.2 to 21.0.
• !36179 (merged) : Add sampling fraction code and analysis for HEC
• !36264 (merged) : Fix peeking of files with only xAOD::EventInfo
• !35986 (merged) : Add functionality to find and remove duplicate FastCaloSim instances from the simulation chain
• !36140 (merged) : Reverting the temporary special reference for HLTtau and restoring default trigger references
• !35899 (merged) : Sweeping !35830 (merged) from master to 21.0.
• !35840 (merged) : FastCaloSimGAN: skip unused layers early in the GAN layer simulation chain
• !35802 (merged) : Update log file diff in post.sh

Link to the full diff between release/21.0.118 and release/21.0.117 is available at https://gitlab.cern.ch/atlas/athena/compare/release/21.0.117...release/21.0.118

Marking as full-build as this pulls in an externals update - FYI @akraszna.