AthenaKernel: delete MsgStreamMember class

MsgStreamMember is not thread-safe and superseded by AthMessaging.

This merge request affects 1 package:

• Control/AthenaKernel

This merge request affects 5 files:

• Control/AthenaKernel/AthenaKernel/MsgStreamMember.h
• Control/AthenaKernel/CMakeLists.txt
• Control/AthenaKernel/share/MsgStreamMember_test.ref
• Control/AthenaKernel/src/MsgStreamMember.cxx
• Control/AthenaKernel/test/MsgStreamMember_test.cxx

Adding @ssnyder as watcher

added Core master review-pending-level-1 labels

CI Result FAILURE (hash de943f93)

	Athena	AthSimulation	AthGeneration	AnalysisBase	AthAnalysis	DetCommon
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
AthAnalysis: number of compilation errors 0, warnings 0
DetCommon: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 52426]

Unrelated failures. Any problems in this MR would show up as compilation failures. So this can be reviewed.

Changes look fine and, as mentioned, failures in the CI are known and unrelated. Approving. Clara (L1)

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit a6efa292

added sweep:ignore label