Fix the check for the password matching username

[pmatseykanets]

Issue:

Problem

When creating/setting the user's password via the User Public API it's possible to set the password that matches the username, which should not be allowed.
The secret mutator was checking for the userInfo.Username as opposed to the user.Username.

Solution

Check the password against the user.Username.

CheckList

• Test
• Docs

[pmatseykanets]

# New user
kubectl create -f - <<EOF
apiVersion: management.cattle.io/v3
kind: User
metadata:
  generateName: u-
enabled: true
username: testuser123456
EOF
user.management.cattle.io/u-kp9n2 created

# The password matches the username
kubectl -n cattle-local-user-passwords create secret generic u-kp9n2 --from-literal=password=testuser123456
error: failed to create secret admission webhook "rancher.cattle.io.secrets" denied the request: password cannot be the same as username

# The password doesn't match the username
kubectl -n cattle-local-user-passwords create secret generic u-kp9n2 --from-literal=password=secretsecret
secret/u-kp9n2 created