Remove particle related benchmarks for gas only dataset

--HG--
branch : yt

benchmarks/benchmarks/small_flash.py

@@ -6,16 +6,6 @@ class SmallFlashSuite:
     def setup(self):
         self.ds = yt.load(self.dsname)
 
-    def time_all_particles(self):
-        dd = self.ds.all_data()
-        dd["all", "particle_velocity_x"]
-        dd["all", "particle_velocity_y"]
-        dd["all", "particle_velocity_z"]
-
-    def time_all_particles_derived(self):
-        dd = self.ds.all_data()
-        dd["all", "particle_velocity_magnitude"]
-
     def time_gas_read(self):
         dd = self.ds.all_data()
         dd["gas", "density"]
@@ -34,12 +24,6 @@ def time_ghostzones(self):
         dd = self.ds.all_data()
         dd["velocity_divergence"]
 
-    def time_particle_quantities(self):
-        dd = self.ds.all_data()
-        dd.quantities.extrema("particle_mass")
-        dd.quantities.extrema("particle_velocity_magnitude")
-        dd.quantities.extrema(["particle_velocity_%s" % ax for ax in 'xyz'])
-
     def time_gas_quantites(self):
         dd = self.ds.all_data()
         dd.quantities.extrema("density")