Revert "system-web-app: fix web app shortcut missing icons in sample SWA and tests"

This reverts commit dbe20fd9.

Reason for revert: Seems to have broken All/SettingsAppIntegrationTest.OmniboxNavigateToSettings/Regular_Crosapi on Linux Chromium OS ASan LSan Tests (1), see https://crbug.com/1455351

Original change's description:
> system-web-app: fix web app shortcut missing icons in sample SWA and tests
>
> Sample SWA and test SWA didn't provide web app shortcuts menu item
> icons.
>
> This CL fixes relevant code and adds icons to WebAppInstallInfo, updates
> SystemWebAppManagerInstallAllAppsBrowserTest.BasicConsistencyCheck to
> verify shortcut menu item icon is provided for each shortcut entry.
>
> Bug: 1427444,1417955
> Change-Id: Ib08880900ea0f23e238602756af263a3749f99f6
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4613592


> Reviewed-by: Dibyajyoti Pal <dibyapal@chromium.org>
> Commit-Queue: Dibyajyoti Pal <dibyapal@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1158130}

Bug: 1427444,1417955, 1455351
Change-Id: If1342e4565c0caf5c9a6ef944f3696422eacbad6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4614520
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Antonio Sartori <antoniosartori@chromium.org>
Owners-Override: Antonio Sartori <antoniosartori@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1158721}