Fix regression in inputs for 'recycling fraction' debug tests

The T_wall setting had been accidentally altered (or failed to merge?)
when the inputs were refactored, causing sqrt(-1) errors. Reset T_wall
to a working value.

moment_kinetics/debug_test/recycling_fraction_inputs.jl

@@ -6,7 +6,7 @@ test_input = OptionsDict("composition" => OptionsDict("n_ion_species" => 1,
                                         "electron_physics" => "boltzmann_electron_response",
                                         "recycling_fraction" => 0.5,
                                         "T_e" => 0.2,
-                                        "T_wall" => 0.1),
+                                        "T_wall" => 2.0),
                   "ion_species_1" => OptionsDict("initial_density" => 1.0,
                                           "initial_temperature" => 1.0),
                   "run_name" => "full-f",