Categorize fractional gates guide as cron-job only (#2497)

Switches the notebook to use an open-access backend. Fixes #2454.

scripts/config/notebook-testing.toml

@@ -22,7 +22,6 @@ notebooks = [
     "docs/guides/dynamic-circuits-considerations.ipynb",
     "docs/guides/dynamical-decoupling-pass-manager.ipynb",
     "docs/guides/error-mitigation-and-suppression-techniques.ipynb",
-    "docs/guides/fractional-gates.ipynb",
     "docs/guides/get-qpu-information.ipynb",
     "docs/guides/local-testing-mode.ipynb",
     "docs/guides/operator-class.ipynb",
@@ -69,6 +68,7 @@ test-strategies.extended = { patch="qiskit-ibm-runtime", backend="test_eagle_us-
 test-strategies.hardware = { patch="qiskit-ibm-runtime-open" }
 notebooks = [
     "docs/guides/algorithmiq-tem.ipynb",
+    "docs/guides/fractional-gates.ipynb",
     "docs/guides/functions.ipynb",
     "docs/guides/get-started-with-primitives.ipynb",
     "docs/guides/ibm-circuit-function.ipynb",