[BUG] MySQL cache driver unable to enumerate minions, breaks manage.present

Description
The MySQL minion cache is unable to enumerate minions and fails when running actions relying on mysql_cache.ls
This causes manage.present to fail.

Setup

Please be as specific as possible and give set-up details.

• [ *] container (Kubernetes, Docker, containerd, etc. please specify)
• [ *] onedir packaging

Steps to Reproduce the behavior
Configure /etc/salt/master with MySQL cache

# /etc/salt/master
cache: mysql
mysql.host: "..."
mysql.port: 3306
mysql.user: saltstack
mysql.password: "..."

Run salt-run manage.status to confirm the minions are present via events

$ salt-run manage.status
- minion1
- minion2
$

The bug:
Run salt-run manage.present which should use the minion cache to determine presence

$ salt-run  manage.present
$

Expected behavior
A clear and concise description of what you expected to happen.

$ salt-run  manage.present
- minion1
- minion2
$

Versions Report
Minion/master running 3006.6

Additional context
The data

MariaDB [salt_cache]> select etcd_key, bank from salt where bank LIKE 'minions/%' limit 2;
+----------+-------------------------------------------------------+
| etcd_key | bank                                                  |
+----------+-------------------------------------------------------+
| data     | minions/minion1            |
| data     | minions/minion2 |
+----------+-------------------------------------------------------+

The code in mysql_cache.py is:

def ls(bank):
    """
    Return an iterable object containing all entries stored in the specified
    bank.
    """
    _init_client()
    query = "SELECT etcd_key FROM {} WHERE bank=%s".format(
        __context__["mysql_table_name"]
    )
    cur, _ = run_query(__context__.get("mysql_client"), query, args=(bank,))
    out = [row[0] for row in cur.fetchall()]
    cur.close()
    return out

It appears to mistakenly return etcd_key instead of the path of the minion. Return looks like ['data', 'data', ... ]. ls would be expected to return ["minion1", "minion2"]