Remove the global tuneup instruction. (#2344)
The error causing this workaround has been fixed and the instruction is
not needed anymore.
diff --git a/test_utilities/bin/dart_test_runner.sh b/test_utilities/bin/dart_test_runner.sh
index 21478f2..5b6ed04 100755
--- a/test_utilities/bin/dart_test_runner.sh
+++ b/test_utilities/bin/dart_test_runner.sh
@@ -27,8 +27,6 @@
echo "###############################"
fi
-# See https://github.com/dart-lang/sdk/issues/25551 for why this is necessary.
-dart pub global run tuneup check
# Only try tests if test folder exist.
if [ -d 'test' ]; then
echo "############# tests ###########"
