Re-order thread initialization to follow logging, and remove a comment.

lib/log no longer uses lib/thread; lib/log only uses lib/lock, which
is at a lower level.

src/lib/thread/compat_threads.c

@@ -130,8 +130,6 @@ subsys_threads_initialize(void)
 const subsys_fns_t sys_threads = {
   .name = "threads",
   .supported = true,
-  /* Threads is used by logging, which is a diagnostic feature, we want it to
-   * init right after low-level error handling and approx time. */
-  .level = -95,
+  .level = -89,
   .initialize = subsys_threads_initialize,
 };