feat(opensearchservice): throw ValidationErrors instead of untyped errors (#34432)

### Issue

Relates to #32569

### Reason for this change

untyped Errors are not recommended

### Description of changes

`ValidationError`s everywhere

### Describe any new or updated permissions being added

None

### Description of how you validated changes

Existing tests. Exemptions granted as this is a refactor of existing code.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

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

Author: mrgrain

packages/aws-cdk-lib/.eslintrc.js

@@ -27,7 +27,6 @@ const noThrowDefaultErrorNotYetSupported = [
   'aws-lambda-destinations',
   'aws-lambda-event-sources',
   'aws-lambda-nodejs',
-  'aws-opensearchservice',
   'aws-scheduler-targets',
   'aws-scheduler',
   'aws-secretsmanager',