##### SUMMARY
Environment variables in plugin do not match Tower credential injector

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
lib/ansible/plugins/inventory/vmware_vm_inventory.py

##### ANSIBLE VERSION
```
ansible 2.8.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python2.7/site-packages/ansible
  executable location = /bin/ansible
  python version = 2.7.5 (default, May 20 2019, 12:21:26) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
```
##### CONFIGURATION
```paste below

```

##### OS / ENVIRONMENT
Red Hat Enterprise Linux Server release 7.5

##### STEPS TO REPRODUCE
use vmware inventory plugin with vCenter credential in Ansible Tower
```yaml
---
plugin: vmware_vm_inventory
validate_certs: False
```


##### EXPECTED RESULTS
inventory should be parsed

##### ACTUAL RESULTS
```paste below
 [WARNING]:  * Failed to parse
/var/lib/awx/projects/_16__ansible_inventory/tests/vmware_vm_inventory.yaml
with auto plugin: No setting was provided for required configuration
plugin_type: inventory plugin: vmware_vm_inventory setting: username
```

if tag_obj.name not in cacheable_results:
                    cacheable_results[tag_obj.name] = {'hosts': []}
                    self.inventory.add_group(tag_obj.name)
        for vm_obj in objects:
            for vm_obj_property in vm_obj.propSet:
                
                
                
                if not vm_obj.obj.config:
                    
                    continue
                current_host = vm_obj_property.val + "_" + vm_obj.obj.config.uuid
                if current_host not in hostvars:
                    hostvars[current_host] = {}
                    self.inventory.add_host(current_host)
                    host_ip = vm_obj.obj.guest.ipAddress
                    if host_ip:
                        self.inventory.set_variable(current_host, 'ansible_host', host_ip)
                    self._populate_host_properties(vm_obj, current_host)
                    
                    if HAS_VSPHERE and self.pyv.with_tags:
                        
                        vm_mo_id = vm_obj.obj._GetMoId()
                        vm_dynamic_id = DynamicID(type='VirtualMachine', id=vm_mo_id)
                        attached_tags = tag_association.list_attached_tags(vm_dynamic_id)
                        for tag_id in attached_tags:
                            self.inventory.add_child(tags_info[tag_id], current_host)
                            cacheable_results[tags_info[tag_id]]['hosts'].append(current_host)
                    
                    vm_power = str(vm_obj.obj.summary.runtime.powerState)