Minor enhancements to custom LDLT implementations #796

Job	Run time
ubuntu-clang14-sanitizers (address-undefined-leak, ./ci/run_address_sanitizer_tests.sh)	15m 10s
ubuntu-clang14-sanitizers (thread, ./ci/run_thread_sanitizer_tests.sh)	14m 8s
bazel	10m 1s
format	1m 4s
clang-tidy	2m 20s
osx-clang	4m 51s
ubuntu-build-documentation	1m 6s
ubuntu-clang14	10m 18s
ubuntu-gcc11	10m 49s
	1h 9m 47s

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