##### SUMMARY
mysql_user module with check_implicit_admin=yes try to connect to database without password. But when login failed doesn't fallback to login_user and login_password credentials.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
mysql_user

##### ANSIBLE VERSION
```
2.9.0
```

##### OS / ENVIRONMENT
Ubuntu 18.04

##### STEPS TO REPRODUCE
```yaml
- name: Update root password for all root accounts
  mysql_user: name=root password={{ mysql_root_password }} login_user=root login_password={{ mysql_root_password }} host={{ item }} check_implicit_admin=yes
  with_items:
    - "{{ current_hostname.stdout | lower }}"
    - 127.0.0.1
    - ::1
    - localhost
```

First run is ok, but on second run Ansible failed when try to connect as root without password and no fallback to login credentials.

##### EXPECTED RESULTS
First run -> root / no password
Other runs -> root / mysql_root_password

##### ACTUAL RESULTS
Provision failed at other as first run

#
#
#
#
import os
try:
    import pymysql as mysql_driver
    _mysql_cursor_param = 'cursor'
except ImportError:
    try:
        import MySQLdb as mysql_driver
        import MySQLdb.cursors
        _mysql_cursor_param = 'cursorclass'
    except ImportError:
        mysql_driver = None
from ansible.module_utils._text import to_native
mysql_driver_fail_msg = 'The PyMySQL (Python 2.7 and Python 3.X) or MySQL-python (Python 2.X) module is required.'
def mysql_connect(module, login_user=None, login_password=None, config_file='', ssl_cert=None, ssl_key=None, ssl_ca=None, db=None, cursor_class=None,