[Fleet] revert package policy validation that caused issue with input groups

[juliaElastic]

Summary

Partially revert #124215 to unblock #125625

Improvement of validation is raised here #125655

To summarize:
Aws package policy generated by elastic-package is rejected with validation errors, however it should be accepted.
The reason is that policy vars present in package definition global vars, are listed under inputs/streams.
This should be accepted according to this: #125625 (comment)

Example package policy that should be valid, see below.

To verify, run this with a valid agent policy id in policy_id, and verify that it is successfully created.

POST /api/fleet/package_policies
{
  "name": "aws-ec2_metrics",
  "description": "",
  "namespace": "ep",
  "policy_id": "ad5e3840-8e4a-11ec-8b0a-59f6cbd7b323",
  "enabled": true,
  "output_id": "",
  "inputs": [
    {
      "type": "aws/metrics",
      "enabled": true,
      "streams": [
        {
          "id": "aws/metrics-aws.ec2_metrics",
          "enabled": true,
          "data_stream": {
            "type": "metrics",
            "dataset": "aws.ec2_metrics"
          },
          "vars": {
            "latency": {
              "value": "10m",
              "type": "text"
            },
            "period": {
              "value": "5m",
              "type": "text"
            },
            "regions": {
              "value": null,
              "type": "text"
            },
            "tags_filter": {
              "value": "- key: Name\n  value: \"elastic-package-test-33138\"",
              "type": "yaml"
            }
          }
        }
      ],
      "vars": {
         "access_key_id": {
           "value": "access_key_id",
           "type": "text"
         },
         "credential_profile_name": {
           "value": "credential_profile_name",
           "type": "text"
         },
         "endpoint": {
           "value": "amazonaws.com",
           "type": "text"
         },
         "proxy_url": {
           "value": "proxy_url",
           "type": "text"
         },
         "role_arn": {
           "value": "role_arn",
           "type": "text"
         },
         "secret_access_key": {
           "value": "secret_access_key",
           "type": "text"
         },
         "session_token": {
           "value": "session_token",
           "type": "text"
         },
         "shared_credential_file": {
           "value": "shared_credential_file",
           "type": "text"
         }
       }
    }
  ],
  "package": {
    "name": "aws",
    "title": "AWS",
    "version": "1.11.4"
  }
}

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[criamico]

LGTM

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 41a77c7
• Storybooks Preview
• Webpack Bundle Analyzer

Metrics [docs]

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
fleet	109.9KB	109.8KB	-106.0B

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
fleet	40	41	+1

Total ESLint disabled count

id	before	after	diff
fleet	48	49	+1

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @juliaElastic

[kibanamachine]

💔 Some backports could not be created

Status	Branch	Result
✅	8.1
✅	8.0
❌	7.17	Backport failed because of merge conflicts You might need to backport the following PRs to 7.17: - [Fleet] fixed undefined error when missing policy vars in template (#124215)

How to fix

Re-run the backport manually:

node scripts/backport --pr 125657

Note: Successful backport PRs will be merged automatically after passing CI.

Questions ?

Please refer to the Backport tool documentation