Remove karma junit output

See https://github.com/matrix-org/matrix-react-sdk/pull/2944

karma.conf.js

@@ -100,7 +100,7 @@ module.exports = function (config) {
 
         // test results reporter to use
         // available reporters: https://npmjs.org/browse/keyword/karma-reporter
-        reporters: ['logcapture', 'spec', 'junit', 'summary'],
+        reporters: ['logcapture', 'spec', 'summary'],
 
         specReporter: {
             suppressErrorSummary: false, // do print error summary
@@ -159,10 +159,6 @@ module.exports = function (config) {
         // how many browser should be started simultaneous
         concurrency: Infinity,
 
-        junitReporter: {
-            outputDir: 'karma-reports',
-        },
-
         webpack: webpack_config,
 
         webpackMiddleware: {