Re-enable util_datadir check disabled in #20744

This should also fix an assert error if a -datadir with a trailing slash
is used on windows. This appears to be a real error and regression
introduced with #20744.

On windows (or at least wine), fs calls that actuallly access the
filesystem like fs::equivalent or fs::exists seem to treat directory
paths with trailing slashes as not existing, so it's necessary to
normalize these paths before using them. This fix adds a
path::lexically_normal() call to the failing assert so it passes.

src/util/system.cpp

@@ -253,7 +253,7 @@ fs::path StripRedundantLastElementsOfPath(const fs::path& path)
         result = result.parent_path();
     }
 
-    assert(fs::equivalent(result, path));
+    assert(fs::equivalent(result, path.lexically_normal()));
     return result;
 }
 } // namespace