feat(elasticsearch): allow plain text password

[mattmatravers]

Fixes #262. Allows users to put passwords in the following format:

  elasticsearch:
    auth:
      username: abc123
      password:
        value: es-plaintextpassword

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)

[szalai1]

This change looks good and makes sense.

Not necessary requests:

• add a commented out value to the main values.yaml with some comment, so it can be found by other
• currently if both secret and plaintext password is given the plain text is used. default to secret one. (this just an opinion).

thanks for the contribution.

[mattmatravers]

This change looks good and makes sense.

Not necessary requests:

• add a commented out value to the main values.yaml with some comment, so it can be found by other
• currently if both secret and plaintext password is given the plain text is used. default to secret one. (this just an opinion).

thanks for the contribution.

Thanks Peter!

I agree on both parts but I tried to follow the existing style. For other auth parameters the "value" takes precedence over the secrets. The values.yaml file doesn't currently contain a reference to the secrets either, so I left it as is. If you'd like me to add it, I can.