docs: remove default solver warning from 25.4 release (#5209)

Author: BradyPlanden

src/pybamm/models/base_model.py

@@ -12,9 +12,6 @@
 import pybamm
 from pybamm.expression_tree.operations.serialise import Serialise
 
-# Only throw the default solver warning once
-warnings.filterwarnings("once", message="The default solver changed to IDAKLUSolver*")
-
 
 class BaseModel:
     """
@@ -421,11 +418,6 @@ def default_solver(self):
         if len(self.rhs) == 0 and len(self.algebraic) != 0:
             return pybamm.CasadiAlgebraicSolver()
         else:
-            warnings.warn(
-                "The default solver changed to IDAKLUSolver after the v25.4.0. release. "
-                "You can swap back to the previous default by using `pybamm.CasadiSolver()` instead.",
-                stacklevel=2,
-            )
             return pybamm.IDAKLUSolver()
 
     @property