Update subresourcee integrity docs for 2.4.9 release

[admanesachin]

Purpose of this pull request

Updated subresource-integrity.md to reflect SRI improvements introduced in 2.4.9 (AC-16041).

Hash Generation

• Added a 2.4.9 version note indicating that SRI hash generation now covers JavaScript assets processed through minification, bundling, and merging.
• Updated the body text to clarify that SHA-256 hashes are generated including minified file variants, and that coverage spans all SCD strategies
  (Standard, Quick, and Compact).
• Updated the collector description to reflect that hashes are now saved to a scoped, per-package repository immediately after each package is deployed,
  rather than after all packages are deployed.
• Clarified that bundled asset hashes are generated at deploy time, while merged asset hashes are captured at runtime and stored in
  pub/static/_cache/merged/sri-hashes.json.

Storage

• Added a 2.4.9 version note indicating that SRI hash files are now scoped by area, theme, and locale.
• Corrected the storage path example from pub/static/adminhtml/sri-hashes.json to pub/static/adminhtml/Magento/backend/en_US/sri-hashes.json.
• Documented the separate merged assets hash file at pub/static/_cache/merged/sri-hashes.json.
• Added an explanation of the performance motivation behind per-scope storage.
• Added a note that partial static content deployments (--area, --theme, --language) only remove and regenerate SRI files matching the specified scope.

JIRA ticket: AC-16041

Affected pages

https://developer.adobe.com/commerce/php/development/security/subresource-integrity

[eug123]

Looks good to me