Remove myself from redundant "leaf node" OWNERS files

R=dpapad@chromium.org

Bug: none
Change-Id: Ifb969cba1b97d54d6aa990cf3598573fcd71bb62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013919
Commit-Queue: Dan Beam <dbeam@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Auto-Submit: Dan Beam <dbeam@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733844}

chrome/browser/resources/downloads/OWNERS

-dbeam@chromium.org
-
 # COMPONENT: UI>Browser>Downloads

chrome/browser/resources/history/OWNERS

 calamity@chromium.org
-dbeam@chromium.org
 
 # COMPONENT: UI>Browser>History

chrome/browser/resources/settings/OWNERS

-dbeam@chromium.org
 dpapad@chromium.org
 dschuyler@chromium.org
 hcarmona@chromium.org

chrome/browser/ui/webui/downloads/OWNERS

 file://components/download/OWNERS
 
-dbeam@chromium.org
-
 per-file *.mojom=set noparent
 per-file *.mojom=file://ipc/SECURITY_OWNERS