Add ValidationException to error closures of operations of event stream

[jasgin]

Background

• What do these changes do?
• Why are they important?

The event stream protocol test operations take constrained input, but do not have ValidationException in the error closures. This is causing failures in CI for smithy-lang/smithy-rs#4399.

Testing

• How did you test these changes?

Tests pass with the changes in place locally.

Links

• Links to additional context, if necessary
• Issue #, if applicable (see here for a list of keywords to use for linking issues)

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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.

[github-actions]

This pull request does not contain a staged changelog entry. To create one, use the ./.changes/new-change command. For example:

./.changes/new-change --pull-requests "#2861" --type feature --description "Add ValidationException to error closures of operations of event stream"

Make sure that the description is appropriate for a changelog entry and that the proper feature type is used. See ./.changes/README or run ./.changes/new-change -h for more information.

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