fix: (1) move "auto outside stroke" back to zrender. Think that's reasonable...

fix: (1) move "auto outside stroke" back to zrender. Think that's reasonable to auto provide this strategy to user.
(2) do not specify insideStroke directly, use zrender auto strategry, otherwise incorrect in emphasis.

src/util/graphic.ts

@@ -803,10 +803,7 @@ export function createTextConfig(
 
     // fill and auto is determined by the color of path fill if it's not specified by developers.
     textConfig.outsideFill = opt.autoColor || null;
-    textConfig.insideStroke = opt.autoColor || null;
-    // Set default stroke, which is useful when label is over other
-    // messy graphics (like lines) in background.
-    textConfig.outsideStroke = 'rgba(255, 255, 255, 0.9)';
+
     // if (!textStyle.fill) {
     //     textConfig.insideFill = 'auto';
     //     textConfig.outsideFill = opt.autoColor || null;