[tests] call server/resetCache between display test cases (#11880)

tests/display/src/RpcDisplayTestCase.hx

@@ -1,5 +1,7 @@
 import haxe.display.Display;
 import haxe.display.Position.Range;
+import haxe.display.Protocol;
+import haxe.Json;
 import utest.Assert;
 import Types;
 
@@ -11,6 +13,13 @@ class RpcDisplayTestCase implements utest.ITest {
 
 	public function new() {}
 
+	@:timeout(3000)
+	public function setup() {
+		var methodArgs = {method: Methods.ResetCache, id: 1, params: {}};
+		var args = ['--display', Json.stringify(methodArgs)];
+		BaseDisplayTestContext.runHaxe(args);
+	}
+
 	// api
 	inline function pos(name)
 		return ctx.pos(name);