Settings Web UI: Remove flattenhtml for os people page

allowexternalscript="true" was removed in
https://chromium-review.googlesource.com/c/chromium/src/+/1980212

As a result this now causes a console error and prevents the people
page from loading in debug builds. Remove flattenhtml as well, since
there does not seem to be a reason to keep it for this file.

Bug: None
Change-Id: I43d92c68b76ae423e53cf4ce9010ee823bf9622c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1982725Reviewed-by: Dan Beam <dbeam@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727527}

chrome/browser/resources/settings/os_settings_resources.grd

@@ -612,8 +612,7 @@
                  type="chrome_html" />
       <structure name="IDR_OS_SETTINGS_PEOPLE_PAGE_HTML"
                  file="chromeos/os_people_page/os_people_page.html"
-                 type="chrome_html"
-                 flattenhtml="true" />
+                 type="chrome_html" />
       <structure name="IDR_OS_SETTINGS_PEOPLE_PAGE_JS"
                  file="chromeos/os_people_page/os_people_page.js"
                  type="chrome_html" />