Remove duplicate check_chemistry() calls from stage validators (#1627)

Co-authored-by: Spencer Bryngelson <sbryngelson@gmail.com>

Author: rayair250-droid

toolchain/mfc/case_validator.py

@@ -2267,7 +2267,6 @@ def validate_simulation(self):
         self.check_continuum_damage()
         self.check_grcbc()
         self.check_probe_integral_output()
-        self.check_chemistry()
 
     def validate_pre_process(self):
         """Validate pre-process-specific parameters"""
@@ -2277,7 +2276,6 @@ def validate_pre_process(self):
         self.check_parallel_io_pre_process()
         self.check_grid_stretching()
         self.check_perturb_density()
-        self.check_chemistry()
         self.check_misc_pre_process()
         self.check_patch_physics()
         self.check_volume_fraction_sum()
@@ -2305,7 +2303,6 @@ def validate_post_process(self):
         self.check_schlieren()
         self.check_surface_tension_post()
         self.check_no_flow_variables()
-        self.check_chemistry()
 
     def validate(self, stage: str = "simulation"):
         """Main validation method