chore: update test for serializing Blob

[ryanking13]

Blob is now serializable (cloudflare/workerd@51d957f)

Since this is a workerd-side change, we don't need any release but we need to update our test

[ask-bonk]

The changes are straightforward:

1. A new positive test is added for Blob serialization via RPC (lines 296-298), verifying that a Blob can be sent through identity() and comes back as a Blob with the correct content.
2. The negative test that expected Blob to throw a DataCloneError is removed, since Blob is now serializable in workerd.

The test logic is clean, consistent with the existing test patterns in the file, and the PR description clearly explains the motivation (workerd commit 51d957f made Blob serializable).

No actionable issues found.

LGTM

github run