chore(ec2): add VPC interface endpoints for EventBridge Scheduler

[amodam-user]

Issue # (if applicable)

Closes #38588

Reason for this change

EventBridge Scheduler supports interface VPC endpoints, but they are currently missing from InterfaceVpcEndpointAwsService. Users must construct the service manually via new InterfaceVpcEndpointAwsService('scheduler'), which is inconsistent with other services and creates a surprise since EVENTBRIDGE points at events (a different service).

Description of changes

Add interface VPC endpoints to packages/aws-cdk-lib/aws-ec2/lib/vpc-endpoint.ts:

• SCHEDULER → com.amazonaws.<region>.scheduler
• SCHEDULER_FIPS → com.amazonaws.<region>.scheduler-fips

Endpoint availability confirmed via AWS docs: https://docs.aws.amazon.com/general/latest/gr/eventbridgescheduler.html (FIPS endpoints available in US, GovCloud, and Canada regions).

Describe any new or updated permissions being added

None

Description of how you validated changes

Confirmed both endpoints exist per the AWS General Reference endpoints table for EventBridge Scheduler. Change mirrors the pattern used for other services (e.g., SAGEMAKER_RUNTIME / SAGEMAKER_RUNTIME_FIPS, COGNITO_IDENTITY / COGNITO_IDENTITY_FIPS).

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[amodam-user]

@pahud thanks for the review notes on #38588. Addressed both items:

• Unit test — added a test.each block in vpc-endpoint.test.ts that synthesizes an interface endpoint for SCHEDULER and SCHEDULER_FIPS in us-east-1 and asserts the rendered ServiceName is com.amazonaws.us-east-1.scheduler and com.amazonaws.us-east-1.scheduler-fips, matching the pattern used for the transcribe test above it.
• README — the aws-ec2 README doesn't enumerate InterfaceVpcEndpointAwsService constants (it links to the class as the canonical list, with a single Keyspaces/ECR usage example). Recent precedent PRs adding new constants (e.g. chore(ec2): add VPC interface endpoints for Cognito Identity #37302 for Cognito Identity) didn't touch the README either, so I left it alone to match convention. Happy to add an entry if there's a specific section you had in mind.

Not adding a China-region test row since Scheduler is not listed as available in cn-north-1 / cn-northwest-1 per the AWS General Reference.