ci: cancel stuck runs; cap ASan wall time; silence path snprintf warning

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.

src/sandbox_exec.c

@@ -566,9 +566,10 @@ static void sc_rewrite(int pid, const char *in, char *out, size_t n) {
 static int sc_abs_ok(const sc_state_t *s, const char *full, int follow,
                      int strict) {
   char path[OS_PATH_MAX], real[OS_PATH_MAX], loc[2 * OS_PATH_MAX + 2];
-  if (strlen(full) >= sizeof(path))
+  size_t flen = strlen(full);
+  if (flen >= sizeof(path))
     return 0;
-  snprintf(path, sizeof(path), "%s", full);
+  memcpy(path, full, flen + 1);
   size_t n = strlen(path);
   while (n > 1 && path[n - 1] == '/')
     path[--n] = 0;