MSBuild logging fails in large builds (when configurations are cached)

[rainersigwald]

Reported by @Tratcher in dotnet/aspnetcore#32482 (comment).

MSBUILD : error MSB1025: An internal failure occurred while running MSBuild.
Microsoft.Build.Shared.InternalErrorException: MSB0001: Internal MSBuild Error: We shouldn't be accessing the ProjectInstance when the configuration is cached.
   at Microsoft.Build.Shared.ErrorUtilities.ThrowInternalError(String message, Exception innerException, Object[] args)
   at Microsoft.Build.BackEnd.BuildRequestConfiguration.get_Project()
   at Microsoft.Build.BackEnd.Logging.NodeLoggingContext.LogProjectStarted(BuildRequest request, BuildRequestConfiguration configuration)
   at Microsoft.Build.BackEnd.Logging.NodeLoggingContext.LogRequestHandledFromCache(BuildRequest request, BuildRequestConfiguration configuration, BuildResult result)
   at Microsoft.Build.BackEnd.Scheduler.LogRequestHandledFromCache(BuildRequest request, BuildResult result)
   at Microsoft.Build.BackEnd.Scheduler.HandleRequestBlockedByNewRequests(SchedulableRequest parentRequest, BuildRequestBlocker blocker, List`1 responses)
   at Microsoft.Build.BackEnd.Scheduler.ReportRequestBlocked(Int32 nodeId, BuildRequestBlocker blocker)
   at Microsoft.Build.Execution.BuildManager.HandleNewRequest(Int32 node, BuildRequestBlocker blocker)
   at Microsoft.Build.Execution.BuildManager.ProcessPacket(Int32 node, INodePacket packet)
   at Microsoft.Build.Execution.BuildManager.<>c__DisplayClass76_0.<Microsoft.Build.BackEnd.INodePacketHandler.PacketReceived>b__0()
   at Microsoft.Build.Execution.BuildManager.ProcessWorkQueue(Action action)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.Build.Execution.BuildManager.EndBuild()

This happens only when the main MSBuild node is under memory pressure, which is how it evaded detection.

The new access here was introduced in 16.9.0 with #5997.

[rainersigwald]

Fortunately (for us to fix this) there's a secret environment variable MSBUILDDEBUGFORCECACHING=1 that pushes MSBuild down this codepath even when it's not under memory pressure, so this is trivially reproducable: set that, then build any multi-project build.