chore(deps): update multer to ^2.1.1 in appengine storage samples

[angelcaamal]

Description

Fixes Internal: b/512910668

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Checklist

• I have followed guidelines from CONTRIBUTING.MD and Samples Style Guide
• Tests pass: npm test (see Testing)
• Lint pass: npm run lint (see Style)
• Required CI tests pass (see CI testing)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This pull request is from a branch created directly off of GoogleCloudPlatform/nodejs-docs-samples. Not a fork.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new sample directory, and I created GitHub Actions workflow for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

Note: Any check with (dev), (experimental), or (legacy) can be ignored and should not block your PR from merging (see CI testing).

[gemini-code-assist]

Code Review

This pull request attempts to update the multer dependency version across several package.json files. However, the specified version ^2.1.1 does not exist on the npm registry, which will cause installation failures. It is recommended to revert to the stable ^1.4.5-lts.1 version, as 2.x versions are currently in pre-release and involve breaking changes.

[angelcaamal]

The CI is failing in the before all hook with an IAM error: The member bindings allUsers and allAuthenticatedUsers are not allowed since public access prevention is enforced. This is related to a GCP project policy restriction (Public Access Prevention) affecting the test setup, and it is unrelated to the multer version bump in this PR