Fix failing test_transform_forward_healpix_iter test

Forces generated flm to always correspond to real signal.
Increases minimum number of iterations as test for round trip error bring within
tolerance sensitive to specific random draws for smaller number of iterations.

Author: matt-graham

tests/test_spherical_base.py

@@ -14,7 +14,6 @@
 sampling_to_test = ["mw", "mwss", "dh", "gl"]
 method_to_test = ["direct", "sov", "sov_fft", "sov_fft_vectorized"]
 reality_to_test = [False, True]
-iter_to_test = [7, 10]
 
 
 @pytest.mark.parametrize("L", L_to_test)
@@ -133,14 +132,12 @@ def test_transform_forward_healpix(
 
 
 @pytest.mark.parametrize("nside", nside_to_test)
-@pytest.mark.parametrize("reality", reality_to_test)
-@pytest.mark.parametrize("iter", iter_to_test)
-def test_transform_forward_healpix_iter(
-    flm_generator, nside: int, reality: bool, iter: int
-):
+@pytest.mark.parametrize("iter", [8, 10])
+def test_transform_forward_healpix_iter(flm_generator, nside: int, iter: int):
     sampling = "healpix"
     L = 2 * nside
-    flm = flm_generator(L=L, reality=True)
+    reality = True
+    flm = flm_generator(L=L, reality=reality)
     f = spherical.inverse(flm, L, sampling=sampling, nside=nside, reality=reality)
     flm_direct = spherical.forward(
         f,