Re-enable one hot unit tests on CPU backend (non-exception cases only) (#2091)

src/ngraph/runtime/cpu/unit_test.manifest

-one_hot_matrix_0
-one_hot_scalar_0_in_3
-one_hot_scalar_1_in_3
-one_hot_scalar_2_in_3
+# one hot tests that expect exceptions
+# Consider removing
 one_hot_scalar_fp_nonint_in_3
 one_hot_scalar_oob_in_3
-one_hot_vector_0
-one_hot_vector_1
 one_hot_vector_1_barely_oob
 one_hot_vector_1_far_oob
-one_hot_vector_1_fp
 one_hot_vector_1_fp_nonint
+
 backwards_batch_norm_three_outputs
 backwards_maxpool_n2_c1_hw5_3x3_str2_max_pad1x2_2x3
 shape_of_scalar