dashboard: Fix the bug that cookie may have conflict with web applications under the same domain (#1443)

sentinel-dashboard/src/main/resources/application.properties

@@ -3,6 +3,9 @@ spring.http.encoding.force=true
 spring.http.encoding.charset=UTF-8
 spring.http.encoding.enabled=true
 
+#cookie name setting
+server.servlet.session.cookie.name=sentinel_dashboard_cookie
+
 #logging settings
 logging.level.org.springframework.web=INFO
 logging.file=${user.home}/logs/csp/sentinel-dashboard.log