build_report: Size exceeds int32

Update size of files to be an int64 because it's exceeding the bounds.

BUG=b:213347395
TEST=./generate.sh

Change-Id: I70cb1c1df0d0ed66bc5a6e48965eca4739b712c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/3453156
Reviewed-by: George Engelbrecht <engeg@google.com>
Reviewed-by: Arthur Bello <artbello@google.com>
Commit-Queue: Benjamin Shai <bshai@google.com>
Reviewed-by: Jack Neus <jackneus@google.com>
3 files changed