DSCS-2313: detect ACO merchants by viewId and normalize scope codes to placeholders

[simonrico]

Description

Changes getCcdmData() in the storefront events collector to detect CCDM merchants
by viewId instead of locale. When viewId is present, scope codes are always
overridden with standard placeholders (STORE_VIEW_CODE, STORE_CODE, WEBSITE_CODE)
regardless of any values configured by the merchant.

Related Issue

https://jira.corp.adobe.com/browse/DSCS-2313

Motivation and Context

locale was the original detection signal for CCDM merchants before viewId was
introduced. viewId is the identifier for CCDM merchants and is used consistently
across the pipeline. This change aligns the collector with that.

How Has This Been Tested?

• Updated existing unit tests to reflect the new behavior
• Added two new test cases: one verifying placeholders are injected even when scope
  codes are also set, and one verifying non-CCDM merchants (no viewId) are unaffected
• Full test suite run: 55/55 tests passing

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.