fix: remove references to autoGenerated secrets and add RDBMS secret in table

[jessesimpson36]

Description

We recently dropped the global.secrets.autoGenerated flag in our helm values.yaml , and we've also added a secret in the RDBMS set of options for the 8.9 version. This PR is updating the Secrets Management documentation page to reflect those two changes.

When should this change go live?

• This is a bug fix, security concern, or something that needs urgent release support. (add bug or support label)
• This is already available but undocumented and should be released within a week. (add available & undocumented label)
• This is on a specific schedule and the assignee will coordinate a release with the Documentation team. (create draft PR and/or add hold label)
• This is part of a scheduled alpha or minor. (add alpha or minor label)
• There is no urgency with this change (add low prio label)

PR Checklist

• The commit history of this PR is cleaned up, using {type}(scope): {description} commit message(s)

• My changes are for an upcoming minor release and are in the /docs directory (version 8.9).
• My changes are for an already released minor and are in a /versioned_docs directory.

• I added a DRI, team, or delegate as a reviewer for technical accuracy and grammar/style:
  • Engineering team review
  • Technical writer review via @camunda/tech-writers unless working with an embedded writer.

[github-actions]

👋 🤖 🤔 Hello, @bkenez! Did you make your changes in all the right places?

These files were changed only in docs/. You might want to duplicate these changes in versioned_docs/version-8.8/.

• docs/self-managed/deployment/helm/configure/secret-management.md

You may have done this intentionally, but we wanted to point it out in case you didn't. You can read more about the versioning within our docs in our documentation guidelines.

[bkenez]

I have a PR for autogenerated secrets removal already, it's mentioned in more places too: #8016

Lets put these two PRs together I suppose 🤔

[github-actions]

[prettier] _{reported by reviewdog 🐶}

camunda-docs/docs/self-managed/deployment/helm/configure/secret-management.md

Lines 50 to 63 in 9274134

	| **Secret** | **Chart values key** | **Type** | **Purpose** |
	| ----------------------------------------- | --------------------------------------------------- | ---------- | ------------------------------------------------------------------------ |
	| **Enterprise License Key** | `global.license.secret` | Internal | Camunda Enterprise license key |
	| **Identity First User Password** | `identity.firstUser.secret` | Internal | Default user password (`demo/demo`) |
	| **OAuth Client Secret (Admin)** | `global.identity.auth.admin.secret` | Internal | OAuth admin client secret for administrative operations |
	| **OAuth Client Secret (Connectors)** | `connectors.security.authentication.oidc.secret` | Internal | OAuth client secret for connectors |
	| **OAuth Client Secret (Orchestration)** | `orchestration.security.authentication.oidc.secret` | Internal | OAuth client secret for Orchestration Cluster |
	| **OAuth Client Secret (Optimize)** | `global.identity.auth.optimize.secret` | Internal | OAuth client secret for Optimize |
	| **Identity External Database Password** | `identity.externalDatabase.secret` | External | Password for external PostgreSQL if using an external DB for Identity |
	| **WebModeler External Database Password** | `webModeler.restapi.externalDatabase.secret` | External | Password for external PostgreSQL if using an external DB for Web Modeler |
	| **SMTP Password** | `webModeler.restapi.mail.secret` | External | SMTP credentials for sending email notifications |
	| **External Elasticsearch Auth** | `global.elasticsearch.auth.secret` | External | Password for external Elasticsearch authentication (basic auth) |
	| **External OpenSearch Auth** | `global.opensearch.auth.secret` | External | Password for external OpenSearch authentication (basic auth) |
	| **RDBMS Auth** | `orchestration.data.secondaryStorage.rdbms.secret` | External | Password for external RDBMS authentication (basic auth) |