[Feature - Jaeger]: Ability to not provide ES_USERNAME

[klubi]

Requirement

In AWS environment, when jaeger runs in kubernetes than it can access OpenSearch via dedicated vpc url.
Using that URL does not require providing any credentials (if fine-grained-access is disabled).

Problem

Using jaeger chart makes it impossible to not provide name that will be passed as ES_USERNAME.
Providing that variable makes it impossible to use OpenSearch as a backend.

Proposal

Would be nice if chart allowed to not provide that value, so it does not get rendered.

I have a working solution, using jaeger-operator (not chart, raw, in-house built manifests).
In that solution, operator takes below Jaeger config:

storage:
    type: elasticsearch
    options:
      es:
        server-urls: https://vpc-redacted-redacted.us-east-1.es.amazonaws.com
        index-prefix: staging-tracing
        tls.skip-host-verify: "true"

and turns it into following manifest

spec:
  containers:
  - args:
    - --es.index-prefix=staging-tracing
    - --es.server-urls=https://vpc-redacted-redacted.us-east-1.es.amazonaws.com
    - --es.tls.enabled=true
    - --es.tls.skip-host-verify=true
    - --sampling.strategies-file=/etc/jaeger/sampling/sampling.json
    env:
    - name: SPAN_STORAGE_TYPE
      value: elasticsearch
    - name: COLLECTOR_ZIPKIN_HOST_PORT
      value: :9411
    - name: COLLECTOR_OTLP_ENABLED
      value: "true"

I can't achieve same config using when using jaeger chart, which results in below failures:

Failed to init storage factory","error":"failed to create primary Elasticsearch client: health check timeout: no Elasticsearch node available

Open questions

No response