DOC/TST: add GH#61764 tag and rename test_linecollection.py

Author: EvMossan

pandas/plotting/_matplotlib/core.py

@@ -1558,6 +1558,8 @@ def _make_plot(self, fig: Figure) -> None:
         *not* time-series and have no stacking or error bars, all columns are
         rendered with a single LineCollection for a large speed-up while keeping
         public behaviour identical to the original per-column path.
+
+        GH#61764
         """
         # decide once whether we can use the LineCollection fast draw
         threshold = 200

pandas/tests/plotting/frame/test_linecollection_speedup.py renamed to pandas/tests/plotting/frame/test_linecollection.py

@@ -1,6 +1,6 @@
 """
 Ensure wide DataFrame.line plots use a single LineCollection
-instead of one Line2D per column (PR #61764).
+instead of one Line2D per column (GH #61764).
 """
 
 import numpy as np