How can I put two contour plots into the same figure while displaying only one legend?

Question

testfig = ContourPlot[Sin[x^2 + y^2], {x, -Pi, Pi}, {y, -Pi, Pi}, PlotLegends -> Automatic];

testfig2 = ContourPlot[Cos[x^2 + y^2], {x, -Pi, Pi}, {y, -Pi, Pi}, PlotLegends -> Automatic]

This produces two plots which have the same legend - not surprising since the plotted function is bounded between $-1$ and $1$.

How can I place the two plots into the same figure and only use one legend? It's easy enough to put them on the same plot using GraphicsGrid, but that yields a figure with two legends.

Answer 1

Clear["Global`*"]

size = 250;

testfig = ContourPlot[Sin[x^2 + y^2],
   {x, -Pi, Pi}, {y, -Pi, Pi},
   ImageSize -> size,
   PlotLegends -> Automatic];

testfig2 = ContourPlot[Cos[x^2 + y^2],
   {x, -Pi, Pi}, {y, -Pi, Pi},
   ImageSize -> size];

Row[{testfig, testfig2}]

EDIT: For a legend below

testfig = ContourPlot[Sin[x^2 + y^2], {x, -Pi, Pi}, {y, -Pi, Pi}, 
   ImageSize -> size];

Legended[Row[{testfig, testfig2}],
 Placed[BarLegend[{"M10DefaultDensityGradient", {-1, 1}}, 
   LegendLayout -> "Row"], Below]]

EDIT 2: For larger legend

Legended[Row[{testfig, testfig2}], Placed[
  BarLegend[{"M10DefaultDensityGradient", {-1, 1}},
   Range[-1, 1, 0.2],
   LegendLayout -> "Row",
   LegendMarkerSize -> 500], Below]]