AI: Config: Move RTMP configs to rtmp{} section. v7.0.64 (#4454)

This PR reorganizes SRS configuration structure by moving RTMP-specific
configurations from global scope to a dedicated `rtmp {}` section, and
includes various cleanups.

**Before (SRS 6.x):**

```nginx
listen 1935;
chunk_size 60000;
max_connections 1000;
```

**After (SRS 7.0+):**

```nginx
max_connections 1000;
rtmp {
    listen 1935;
    chunk_size 60000;
}
```

Cleanup:

* Removed unused threads_interval configuration and related code
* Cleaned up reload handlers and removed obsolete functionality

---------

Co-authored-by: OSSRS-AI <winlinam@gmail.com>

trunk/conf/origin.hls.only1.conf

@@ -2,11 +2,15 @@
 # @see https://ossrs.io/lts/en-us/docs/v7/doc/reuse-port
 # @see full.conf for detail config.
 
-listen              1935;
 max_connections     1000;
 pid                 ./objs/origin.hls.only1.pid;
 daemon              off;
 srs_log_tank        console;
+
+# RTMP server configuration
+rtmp {
+    listen              1935;
+}
 http_server {
     enabled         on;
     listen          8080;