tst_QStringApiSymmetry: eliminate one duplicate of a mid_data() row

There were two copies of the same line in mid_data(), leading to
duplicated data row tags.

Change-Id: Ia21e855ff781b13fe18c932cff48cb0aabd12750
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp

@@ -2019,7 +2019,6 @@ void tst_QStringApiSymmetry::mid_data()
     ROW(abc, 0, -1, abc, abc);
     ROW(abc, 0, 5, abc, abc);
     ROW(abc, -1, 1, abc, null);
-    ROW(abc, -1, 2, abc, a);
     ROW(abc, -1, 4, abc, abc);
     ROW(abc, 1, -1, bc, bc);
     ROW(abc, 1, 1, bc, b);