Fix all sanitizer warnings

I think we should try to fix all the clang sanitizer warnings.

There are currently a few handfuls of warnings from the integer sanitizer. Almost all are in the routing filter, which does lots of bit manipulation, so it might just be a matter of annotating them so clang ignores them.

The kvstore iterator also has a memory leak that does not look easy to resolve. Essentially, it appears that if you run an iterator to its end and then destroy it, it does not deallocate some memory. This can be discovered by running the tests with address sanitizer enabled.

Once we get to zero sanitizer warnings, we should consider adding sanitized runs to CI.

Start by running the tests with AddressSanitizer and IntegerSanitizer enabled, then separate the routing filter warnings from the kvstore iterator leak. Trace the iterator through its end-of-iteration and destruction paths, and inspect the routing filter's bit manipulation before deciding whether annotations are appropriate. Done means zero sanitizer warnings and a decision on adding sanitized runs to CI.