[gardener] Revert "Add URL usage observation in the WebsiteMetrics component"

This reverts commit 785e5a376c18c7a5d24988d3fcdffc22756f17c2.

Reason for revert: cause build breakage https://ci.chromium.org/ui/p/chromium/builders/ci/Deterministic%20Linux/42186/overview and tree is closed

Original change's description:
> Add URL usage observation in the WebsiteMetrics component
>
> This change updates the WebsiteMetrics event observer to also track URL
> usage so external components are notified of URL usage as they are being
> recorded.
>
> Changes for tracking the additional usage snapshot in the pref store for
> enterprise reporting purposes will be done in a separate CL.
>
> Bug: b:293364163
> DD: go/i&i_website_usage
> Change-Id: I770ed611bd0268f2225ee18493f6efd7fc9e92cd
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4763416
> Reviewed-by: Dominick Ng <dominickn@chromium.org>
> Commit-Queue: Vignesh Shenvi <vshenvi@google.com>
> Reviewed-by: Hong Xu <xuhong@google.com>
> Reviewed-by: Leonid Baraz <lbaraz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1183511}

Bug: b:293364163
Change-Id: I6cc01069858ec44f64552a14e4c2978780271767
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4776717
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Ming-Ying Chung <mych@chromium.org>
Reviewed-by: Takashi Sakamoto <tasak@google.com>
Owners-Override: Ming-Ying Chung <mych@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1183520}

• chrome/browser/apps/app_service/metrics/website_metrics.cc[diff]
• chrome/browser/apps/app_service/metrics/website_metrics.h[diff]
• chrome/browser/apps/app_service/metrics/website_metrics_browsertest.cc[diff]