[Python/1D] Retain user-specified products in counterflow premixed flame

When using the 'auto' solver option, user-provided arguments to
set_initial_guess were not being saved for subsequent calls to set_initial_guess
within Sim1D.solve, causing the solution to always be for equilibrated products.

interfaces/cython/cantera/onedim.py

@@ -1165,7 +1165,7 @@ def set_initial_guess(self, equilibrate=True):
         will be set to the equilibrium state of the reactants mixture.
         """
 
-        super().set_initial_guess()
+        super().set_initial_guess(equilibrate=equilibrate)
 
         Yu = self.reactants.Y
         Tu = self.reactants.T