fixed clickthrough handling for duplicate s_kwcid/ef_id query params

[carterworks]

Description

• added regression coverage for malformed URLs with duplicate s_kwcid values at both unit and integration levels.
• normalized clickthrough query params so handleClickThrough safely handles string | string[] and uses the first value when duplicates are present.
• updated release metadata with a patch changeset for this consumer-facing bug fix.

Related Issue

• Jira: https://jira.corp.adobe.com/browse/PDCL-14903
• Closes Error Handling Issue: startsWith Called on Array When Multiple s_kwcid Query Parameters Present #1430

Motivation and Context

Malformed URLs can contain duplicate query params. queryString.parse may return arrays in that case, which caused skwcid.startsWith to throw and prevented clickthrough conversion tracking. This change prevents runtime errors and preserves conversion tracking by coercing duplicate values to the first entry.

Screenshots (if appropriate):

N/A

Checklist:

• I have signed the Adobe Open Source CLA or I'm an Adobe employee.
• I have made any necessary test changes and all tests pass.
• I have run the Sandbox successfully.
• I have added a Changeset (pnpm changeset) or it is not necessary because this PR is not consumer-facing.

[changeset-bot]

🦋 Changeset detected

Latest commit: 6bbbda3

The changes in this PR will be included in the next version bump.

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