Update the mapping to work with remoteRegistry

Now that the remoteRegistry is part of the ModuleInstance, we can
retrieve the parsed data from the env var and use it when setting up
the mapping for the current vu.

browser/mapping.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"os"
 
 	"github.com/dop251/goja"
 
@@ -36,7 +35,7 @@ func mapBrowserToGoja(vu moduleVU) *goja.Object {
 		obj = rt.NewObject()
 		// TODO: Use k6 LookupEnv instead of OS package methods.
 		// See https://github.com/grafana/xk6-browser/issues/822.
-		wsURL, isRemoteBrowser = IsRemoteBrowser(os.LookupEnv)
+		wsURL, isRemoteBrowser = vu.remoteRegistry.IsRemoteBrowser()
 		browserType            = chromium.NewBrowserType(vu)
 	)
 	for k, v := range mapBrowserType(vu, browserType, wsURL, isRemoteBrowser) {