fix: re-enable PlzDedicatedWorker feature

[deepak1556]

Fixes #244143

Refs #244143 (comment) for context

[mjbvz]

Thank you for tracking this down!

[deepak1556]

@mjbvz I have made an isolated sample to demonstrate the clients chosen when the feature is disabled vs enabled at #244143 (comment).

Tl:dr,

• With the feature disabled: page, dedicated worker main resource, dedicated worker sub resources, blob worker all use the same window clients (i-e the frame the workers are associated with)
• With the feature enabled:
  • page and dedicated worker main resource share the same client
  • dedicated worker sub resources has a separate worker client that can be obtained via self.clients.get
  • blob worker has a separate worker client that cannot be obtained via self.clients.get and needs to rely on self.clients.matchAll