Fix expected plugins test for transport-nio

We have a packaging test that tries to install all plugins, and then
asserts that all expected plugins are installed. The expected plugins
are dervied from the list of plugins in the plugins sub-project. The
plugin transport-nio was recently added here, but explicit commands to
install and remove this plugin were never added. This commit addresses
this.

Author: jasontedor

qa/vagrant/src/test/resources/packaging/tests/module_and_plugin_test_cases.bash

@@ -271,6 +271,10 @@ fi
     install_and_check_plugin store smb
 }
 
+@test "[$GROUP] install transport-nio plugin" {
+    install_and_check_plugin transport nio
+}
+
 @test "[$GROUP] check the installed plugins can be listed with 'plugins list' and result matches the list of plugins in plugins pom" {
     "$ESHOME/bin/elasticsearch-plugin" list | cut -d'@' -f1 > /tmp/installed
     compare_plugins_list "/tmp/installed" "'plugins list'"
@@ -373,6 +377,10 @@ fi
     remove_plugin store-smb
 }
 
+@test "[$GROUP] remove transport-nio plugin" {
+    remove_plugin transport-nio
+}
+
 @test "[$GROUP] start elasticsearch with all plugins removed" {
     start_elasticsearch_service
 }