[OTel] [AWS] Extend AWS ELB support to cover Classic LB, Network LB, GatewayLB

[agithomas]

• Enhancement

Proposed commit message

Add Classic, Network, and Gateway Load Balancer support to AWS CloudWatch OTel input

Extend the aws_cloudwatch_input_otel package with three new policy
templates — aws.elb_classic (AWS/ELB), aws.elb_network (AWS/NetworkELB),
and aws.elb_gateway (AWS/GatewayELB) — so all four ELB types can be
collected from a single integration.

Set autodiscover_limit to 250 for every ELB template to prevent the
silent metric truncation we observed when the default of 100 was exceeded
(NLB alone produced 189 metric/dimension combinations with just 5 load
balancers).

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Author's Checklist

• Package upgrading testing
• Integration testing

How to test this PR locally

• elastic-package build && elastic-package stack up -v -d --services package-registry

Screenshots

Discover view

Configuration interface

[github-actions]

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[elastic-vault-github-plugin-prod]

✅ All changelog entries have the correct PR link.

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💚 Build Succeeded

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• Commit: e3357ff

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Package aws_cloudwatch_input_otel - 0.5.0 containing this change is available at https://epr.elastic.co/package/aws_cloudwatch_input_otel/0.5.0/