##### 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

elements: str
  login_db:
    description:
    - Database name to connect to.
    - It makes sense if I(login_user) is allowed to connect to a specific database only.
    type: str
  exclude_fields:
    description:
    - List of fields which are not needed to collect.
    - "Supports elements: C(db_size). Unsupported elements will be ignored"
    type: list
    elements: str
    version_added: '2.10'
author:
- Andrew Klychkov (@Andersson007)
extends_documentation_fragment: mysql
'''
EXAMPLES = r'''
# Display info from mysql-hosts group (using creds from ~/.my.cnf to connect):
# ansible mysql-hosts -m mysql_info
# Display only databases and users info:
# ansible mysql-hosts -m mysql_info -a 'filter=databases,users'
# Display only slave status:
# ansible standby -m mysql_info -a 'filter=slave_status'
# Display all info from databases group except settings:
# ansible databases -m mysql_info -a 'filter=!settings'
- name: Collect all possible information using passwordless root access
  mysql_info:
    login_user: root
- name: Get MySQL version with non-default credentials