update default value of max_idle_threads to keep consistent with libfuse (deepseek-ai#350)

Author: nautaa

configs/hf3fs_fuse_main.toml

@@ -15,7 +15,7 @@ io_job_deq_timeout = '1ms'
 io_jobq_size = 1024
 iov_limit = '1MB'
 max_background = 32
-max_idle_threads = 10
+max_idle_threads = -1
 max_jobs_per_ioring = 32
 max_readahead = '16MB'
 max_threads = 256

src/fuse/FuseConfig.h

@@ -31,7 +31,7 @@ struct FuseConfig : public ConfigBase<FuseConfig> {
   CONFIG_HOT_UPDATED_ITEM(enable_read_cache, true);
   CONFIG_HOT_UPDATED_ITEM(fsync_length_hint, false);  // for test
   CONFIG_HOT_UPDATED_ITEM(fdatasync_update_length, false);
-  CONFIG_ITEM(max_idle_threads, 10);
+  CONFIG_ITEM(max_idle_threads, -1);
   CONFIG_ITEM(max_threads, 256);
   CONFIG_ITEM(max_readahead, 16_MB);
   CONFIG_ITEM(max_background, 32);