Remove incorrect 2D hyper_cleaning prohibition

GLM divergence cleaning is valid in 2D. The z_cc access was already
guarded with `if (p > 0)` in 22304a1. The prohibition broke the
existing 2D hyper_cleaning, mhd_rotor, and orszag_tang tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

toolchain/mfc/case_validator.py

@@ -1029,7 +1029,6 @@ def check_mhd_simulation(self):
         relativity = self.get('relativity', 'F') == 'T'
         hyper_cleaning = self.get('hyper_cleaning', 'F') == 'T'
         n = self.get('n', 0)
-        p = self.get('p', 0)
 
         self.prohibit(mhd and riemann_solver is not None and riemann_solver not in [1, 4],
                      "MHD simulations require riemann_solver = 1 (HLL) or riemann_solver = 4 (HLLD)")
@@ -1041,8 +1040,6 @@ def check_mhd_simulation(self):
                      "Hyperbolic cleaning requires mhd to be enabled")
         self.prohibit(hyper_cleaning and n is not None and n == 0,
                      "Hyperbolic cleaning is not supported for 1D simulations")
-        self.prohibit(hyper_cleaning and n is not None and n > 0 and p is not None and p == 0,
-                     "Hyperbolic cleaning is not supported for 2D simulations")
 
 
     def check_igr_simulation(self):  # pylint: disable=too-many-locals