remove uneccessary AWS_ASSERT() #741

Job	Run time
clang-sanitizers (,thread)	2m 48s
linux-compat (manylinux2014-x64)	2m 30s
linux-shared-libs	2m 18s
clang-sanitizers (,address,undefined)	2m 59s
linux-compiler-compat (clang-3)	2m 33s
linux-compat (manylinux2014-x86)	2m 12s
linux-compiler-compat (clang-6)	2m 59s
linux-compat (fedora-34-x64)	2m 8s
windows	4m 19s
linux-compiler-compat (clang-8)	3m 50s
linux-compat (opensuse-leap)	2m 58s
linux-compat (rhel8-x64)	2m 59s
downstream	2m 26s
linux-compiler-compat (clang-9)	3m 18s
linux-compat (al2-x64)	2m 1s
osx	2m 12s
windows-shared-libs	3m 47s
windows-vc14 (x86)	2m 51s
linux-compiler-compat (clang-10)	3m 45s
windows-vc14 (x64)	4m 49s
linux-compiler-compat (clang-11)	2m 59s
linux-compiler-compat (gcc-4.8)	2m 5s
linux-compiler-compat (gcc-5)	2m 14s
linux-compiler-compat (gcc-6)	2m 41s
linux-compiler-compat (gcc-7)	2m 47s
linux-compiler-compat (gcc-8)	2m 40s
	1h 15m 8s

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