The sanitizers job wedged the only runner by printing AddressSanitizer
DEADLYSIGNAL forever (Docker without SYS_PTRACE). Concurrency now cancels
in-progress jobs on a new push, and make asan is wrapped in timeout -s KILL
480 with shallow ASAN_OPTIONS.
Also copy the path with memcpy after the length check so -O1 asan builds
do not warn about snprintf truncation into OS_PATH_MAX.