helm chart v2 global.database.user not honored when using secret for db password

### Helm Chart Version

v2.0.19

### What step the error happened?

On deploy

### Relevant information

documentation on upgrading from v1 to v2 is quite clear about use of `global.database.user` should override the use of a secret key when set.

However I have the situation where I am trying to set my values like this:

```
global:
database:
secretName: psql
user: airbyte_something

```

And my secret `psql` has only a single key with the password

THis worked fine in v1 chart and is a good pattern for us to operate the helm chart, avoiding storing the database user as a secret.

However this fails in v2. It seems that the use of database.secretName is not well documented interaction about setting the database user in the secret.

In the chart, can we not just expose the environment from a config map *if* the global.database.user is provided? Rather than always trying to store it in a secret?

### Relevant log output

```shell

```