Config: Enable safe sampler overrides by default

* Provides safe fallback samplers, intended for better out-of-the-box support for clients that do not pass sampler params

sampler_overrides/safe_defaults.yml

@@ -0,0 +1,10 @@
+# Minimal "safe" fallback settings for most models, used when the frontend doesn't supply any settings
+# with a request.
+
+temperature:
+  override: 0.8
+  force: false
+
+top_p:
+  override: 0.9
+  force: false