AdminUser not work as expected.

Hi team:

As refer from this link: https://doris.apache.org/zh-CN/docs/install/cluster-deployment/k8s-deploy/root-user-use/ I'm trying to set root password.

Step 1: apply DorisCluster without add `adminUser.name` and `adminUser.password`. the default empty password works for me, both be & fe start well.
Step 2: login doris with mysql cli, run `SHOW ALL GRANTS;` and `set password for 'root' = password('pwd')`, verify login with mysql cli new password.
Step 3: update DorisCluster and add `adminUser.name` and `adminUser.password`, apply by kubectl. new started BE continuing log the error message.

The following error in BE pod as follow:
```
[Thu Jun 13 03:42:23 UTC 2024] [info] use root no password show frontends result ERROR 1045 (28000): Access denied for user 'root@172.24.171.144' (using password: NO) .
ERROR 1045 (28000): Access denied for user 'root@172.24.171.144' (using password: YES)
```

Images:
1. selectdb/doris.k8s-operator:1.5.2
2. selectdb/doris.be-ubuntu:2.1.3
3. selectdb/doris.fe-ubuntu:2.1.3

Also check the issue: https://github.com/selectdb/doris-operator/issues/131