## Check for existing issues

- [x] I have searched existing issues and this appears related to (but not resolved by): - #13544 - #21716

## What happened?

When deploying `litellm-helm` `1.1.0` via ArgoCD with bundled Postgres (`db.deployStandalone=true`) and `postgresql.auth.existingSecret` set, LiteLLM still uses/creates `litellm-dbcredentials` in a way that drifts from the intended secret.

In our test, `litellm-credentials` had the correct password, but `litellm-dbcredentials` ended up with a different/default value (e.g. `NoTaGrEaTpAsSwOrD`). LiteLLM then failed Prisma DB auth (`P1000`) and stayed in `CrashLoopBackOff`.

## What I expected

- If `db.dbCredentialsSecretName` and `postgresql.auth.existingSecret` are both set to the same Secret, all DB auth values should remain consistent. - The chart should not render or preserve conflicting DB credentials that make LiteLLM fail against the bundled Postgres.

## Environment

- Chart: `litellm-helm:1.1.0` - Deployment method: ArgoCD `Application` - Cluster: k3s - LiteLLM image: `ghcr.io/berriai/litellm:main-v1.83.14-stable` - Postgres image: `bitnamilegacy/postgresql`

## Steps to Reproduce

1. Create `litellm-credentials` s…