Revert "[Files App] Makes Camera folder modifiable"

This reverts commit e9e022ce.

Reason for revert: Per UI review, camera folder should be non-modifiable.

Original change's description:
> [Files App] Makes Camera folder modifiable
>
> Per discussion with Files team, we agree that Camera folder should still
> be modifiable.
>
> Bug: 1127587
> Test: Manually
> Change-Id: I22a9e3eca0b7fb71bd883c37bb0e6a30509e8b80
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2477707
> Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
> Commit-Queue: Wei Lee <wtlee@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#820680}

TBR=lucmult@chromium.org,wtlee@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1127587
Change-Id: Iaaa95f90958b3a539c3f32254d784c75dd8ad39c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2505705Reviewed-by: Wei Lee <wtlee@chromium.org>
Commit-Queue: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822072}

ui/file_manager/file_manager/common/js/util.js

@@ -1238,6 +1238,9 @@ util.isNonModifiable = (volumeManager, entry) => {
     if (util.isPluginVmEnabled() && entry.fullPath === '/PvmDefault') {
       return true;
     }
+    if (util.isFilesCameraFolderEnabled() && entry.fullPath === '/Camera') {
+      return true;
+    }
   }
 
   if (volumeInfo.volumeType === VolumeManagerCommon.RootType.CROSTINI &&