Fixed a bug upload boundary calculation in SteamUpload #1516

Job	Run time
MemoryTest (glibc_debug)	13m 15s
Linux (ubuntu:23.04)	17m 13s
MemoryTest (sanitize_address)	13m 31s
macos10	0s
Linux (ubuntu:22.04)	13m 34s
MemoryTest (sanitize_others)	13m 43s
Linux (ubuntu:20.04)	13m 16s
MemoryTest (sanitize_thread)	13m 30s
Linux (debian:bookworm)	13m 53s
MemoryTest (valgrind)	35m 37s
Linux (debian:bullseye)	15m 25s
Linux (debian:buster)	14m 38s
Linux (rockylinux:9)	16m 59s
Linux (rockylinux:8)	14m 6s
Linux (centos:centos7)	20m 24s
Linux (fedora:38)	3m 50s
Linux (fedora:37)	14m 22s
Linux (opensuse/leap:15)	14m 13s
Linux (alpine:3.17)	14m 52s
	4h 36m 21s

Provide feedback