another test fix

Author: nschloe

test/test_barchart_legend_reference.tex

@@ -2,14 +2,7 @@
 
 \begin{axis}[
 legend cell align={left},
-legend style={
-  fill opacity=0.8,
-  draw opacity=1,
-  text opacity=1,
-  at={(0.5,0.91)},
-  anchor=north,
-  draw=white!80!black
-},
+legend style={fill opacity=0.8, draw opacity=1, text opacity=1, draw=white!80!black},
 tick align=outside,
 tick pos=left,
 x grid style={white!69.019608!black},