Fix process.env.profile when --profile isn't set in run-multiple mode (#4131)

Author: mirao

lib/command/run-multiple.js

@@ -28,7 +28,9 @@ let processesDone;
 
 module.exports = async function (selectedRuns, options) {
   // registering options globally to use in config
-  process.env.profile = options.profile;
+  if (options.profile) {
+    process.env.profile = options.profile;
+  }
   const configFile = options.config;
 
   const testRoot = getTestRoot(configFile);