Test build log file is ~4GB with diag verbosity. With normal it's about 20MB.
This seems to speed up the test build for me considerably.
See dotnet/coreclr#7916.
Commit migrated from https://github.com/dotnet/coreclr/commit/
d3e9e0013c551ec6741af0a45eb6b234089afe74
set __BuildLog=%__LogsDir%\%__BuildLogRootName%_%__BuildOS%__%__BuildArch%__%__BuildType%.log
set __BuildWrn=%__LogsDir%\%__BuildLogRootName%_%__BuildOS%__%__BuildArch%__%__BuildType%.wrn
set __BuildErr=%__LogsDir%\%__BuildLogRootName%_%__BuildOS%__%__BuildArch%__%__BuildType%.err
-set __msbuildLog=/flp:Verbosity=diag;LogFile="%__BuildLog%"
+set __msbuildLog=/flp:Verbosity=normal;LogFile="%__BuildLog%"
set __msbuildWrn=/flp1:WarningsOnly;LogFile="%__BuildWrn%"
set __msbuildErr=/flp2:ErrorsOnly;LogFile="%__BuildErr%"