[BUG] Elastic Integration is failling when empty value is present in tags

[ssrahul96]

Agent Environment

Agent 7.57.2 - Commit: 38ba0c7 - Serialization version: v5.0.130 - Go version: go1.22.7

Describe what happened:
We had a empty tag value in `conf.d/elastic.d/conf.yaml'

instances:
  - url: 'host:port'
    tags:
      - abc:

elastic integration was failing with error when we run datadog-agent status

Loading Errors
  ==============
    elastic
    -------
      Core Check Loader:
        Check elastic not found in Catalog

      Python Check Loader:
        could not configure check instance for python check elastic: yaml: unmarshal errors:
  line xxx: cannot unmarshal !!map into string

when we checked the datadog-agent checkconfig, the empty tag is parsed as null, which is valid.

=== elastic check ===
Configuration provider: file
Configuration source: file:/etc/datadog-agent/conf.d/elastic.d/conf.yaml
Config for instance ID: elastic:a9babc1486e14eb6
cluster_stats: false
index_stats: false
pending_task_stats: true
pshard_stats: true
tags:
- abc: null

What we understood is that, the Golang parser parses the empty as null, where as the python parser fails to parse.

Describe what you expected:

Steps to reproduce the issue:

Additional environment details (Operating System, Cloud provider, etc):

[jeremy-hanna]

👋 Hello! Thanks for bringing this inconsistency with checkconfig to our attention @ssrahul96.

I believe the error thrown by the status is correct as Go cannot parse the config yaml formatted like this and null is not a valid tag value. checkconfig should also error so I will look into why it isn't.

If you're looking to submit an empty tag value to our backend please use an empty string, eg:

instances:
  - url: 'host:port'
    tags:
      - abc: ""

I will close out this issue but feel free to re-open or contact support if you are still having configuration issues with this.