Change default value of allow_startup_shutdown param to 1

Setting this parameter to 0, which is also its default value, could
result in an infeasibility since max_shutdown_power_constraint_rule
(which only allows Provide_Power_Shutdown_MW = 0) is incompatible with
ramp_during_shutdown_constraint_rule (which enforces the
Shutdown_Ramp_Rate_MW_Per_Tmp).

gridpath/project/operations/operational_types/gen_commit_unit_common.py

@@ -1182,7 +1182,7 @@ def get_startup_types_by_project(mod, g):
         Param(
             getattr(m, "GEN_COMMIT_{}".format(BIN_OR_LIN)),
             within=Boolean,
-            default=0,
+            default=1,
         ),
     )