regenerate solutions as part of building the managed tracer (#6608)

## Summary of changes

the target `RegenerateSolutions` was not called by anything else. Added
it to `BuildManagedTracerHome` so that it'd run on `BuildTracerHome`,
which I assume(d) would regenerate everything that needs to

tracer/build/_build/Build.cs

@@ -206,7 +206,8 @@ void DeleteReparsePoints(string path)
         .DependsOn(DownloadLibDdwaf)
         .DependsOn(CopyLibDdwaf)
         .DependsOn(CreateMissingNullabilityFile)
-        .DependsOn(CreateTrimmingFile);
+        .DependsOn(CreateTrimmingFile)
+        .DependsOn(RegenerateSolutions);
 
     Target BuildManagedTracerHomeR2R => _ => _
         .Unlisted()