[release/6.0] Remove more unused Docker files (#42247)

* [release/6.0] Remove more unused Docker files
- clean up the old SystemdActivation files
- follow-up work that's similar to c5c8f43

* [release/6.0] Give up on Build.Server.Amd64.VS2019.BT.Open
- `cherry-pick` part of 0394ac7
- was "Try out 1es images (#41400)"

Co-authored-by: Brennan <[email protected]>
Co-authored-by: William Godbe <[email protected]>

Author: 3 people