gui: Do not use OpenGL for pyqtgraph

- Fix Painter path exceeds +/-32767 pixels bug
- Plotting with OpenGL has worse performance
    - See pyqtgraph Issue #2227

fast-servo/linien-gui-do-not-use-opengl.patch

@@ -0,0 +1,13 @@
+diff --git a/linien-gui/linien_gui/ui/plot_widget.py b/linien-gui/linien_gui/ui/plot_widget.py
+index f3b81ce..7d865a3 100644
+--- a/linien-gui/linien_gui/ui/plot_widget.py
++++ b/linien-gui/linien_gui/ui/plot_widget.py
+@@ -40,7 +40,7 @@ from pyqtgraph.Qt import QtCore
+ # NOTE: this is required for using a pen_width > 1. There is a bug though that causes
+ # the plot to be way too small. Therefore, we call PlotWidget.resize() after a while
+ pg.setConfigOptions(
+-    useOpenGL=True,
++    useOpenGL=False,
+     # by default, pyqtgraph tries to clean some things up using atexit. This causes
+     # problems with rpyc objects as their connection is already closed. Therefore, we
+     # disable this cleanup.

flake.nix

@@ -32,6 +32,7 @@
             ./fast-servo/linien-server-fast-servo-hardware-specific.patch
             ./fast-servo/linien-gui-fast-servo-hardware-specific.patch
             ./fast-servo/linien-gui-add-afe_gain-combo-boxes.patch
+            ./fast-servo/linien-ui-do-not-use-opengl.patch
             ./fast-servo/linien-client-ssh-port-change.patch
             ./fast-servo/linien-server-fast-servo.patch
             ./fast-servo/linien-server-cli.patch