Revert "Capability Delegation: match payment-request identifier with spec."

This reverts commit 510b074b.

Reason for revert: failing tests https://crbug.com/1286707#c2

Original change's description:
> Capability Delegation: match payment-request identifier with spec.
>
> The proposed spec [1] specifies a capability through the name defined
> for Permissions Policy [2].  This CL makes the implementation match the
> proposal.
>
> [1] https://wicg.github.io/capability-delegation/spec.html
> [2] https://github.com/w3c/webappsec-permissions-policy/blob/main/features.md
>
> Bug: 1130558
> Change-Id: I926aa030603cfeea10c71fc19f2b232c0d6a5702
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3372328


> Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
> Reviewed-by: David Bokan <bokan@chromium.org>
> Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#957608}

Bug: 1130558, 1286707
Change-Id: I4e373d094a265fb8148798f3ee0381a3d3cd09a9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3380538
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Hazem Ashmawy <hazems@chromium.org>
Owners-Override: Hazem Ashmawy <hazems@chromium.org>
Auto-Submit: Hazem Ashmawy <hazems@chromium.org>
Cr-Commit-Position: refs/heads/main@{#958040}