Remove unnecessary chown for /data/misc/update_engine_log

mkdir will set the correct owner for the directory if the file already
exists, so there is no need for calling chown.

Bug: 397893018
Test: Flash software without this patch. Flash software with this
     CL on top, keep userdata. Confirm that group has changed.
(cherry picked from https://partner-android-review.googlesource.com/q/commit:514212e082ec9d6b750273688f94b776a08a7dba)
Merged-In: I3a9b743897ee119d9dfcf425736764319696de2a
Change-Id: I3a9b743897ee119d9dfcf425736764319696de2a