Fix based on Coverity and Sonar audits (part 6) (#22334)

pulse: use int loop variable when negating to STREAM_HANDSHAKE enum Sonar c:S876: chart_by_reason() iterated with `size_t i` and passed `-i` to stream_handshake_error_to_string(STREAM_HANDSHAKE). The unary minus on the unsigned counter wrapped to a huge unsigned value that then narrowed to int through implementation-defined conversion (C99 6.3.1.3). It happens to produce the correct -i on two's-complement platforms but is fragile and unportable. Change the loop variable to `int`. The loop bound STREAM_HANDSHAKE_NEGATIVE_MAX is 40, well within int range, and the b->rd[] array has more than enough entries for the same index. The negation is now well-defined signed arithmetic. Co-authored-by: Costa Tsaousis <costa@netdata.cloud>