Don't preserve file attributes when pulling bugreport file...

...otherwise it could have weird dates when the device clock is wrong.

Test: m -j32 adb && ./out/host/linux-x86/bin/adb bugreport test.zip && ls -l test.zip
Test: m -j32 adb_test && ./out/host/linux-x86/nativetest64/adb_test/adb_test

Fixes: 63927360

Change-Id: I3f87277f1acb97212a87b89639e42b6d7d300faa