[NFC] Remove the -instcombine flag from strict-fadd.ll

This also fixes a CHECK line in @fadd_strict_unroll which ensures the
changes made to fixReduction() to support in-order reductions with
unrolling are being tested correctly.

GitOrigin-RevId: 93f54fae9dda7d5d89711eb97f1ee44de6ce1ff7
1 file changed