RESPONDER: fixed an issue with 'client_idle_timer'

As it was implemented previously, effective period was 1.5*client_idle_timeout
instead of `client_idle_timeout` as documented.

Log with default value - 60 - before a fix:
```
(:49:12): [nss] [setup_client_idle_timer] (0x4000): Idle timer re-set for client [0x557af16f31b0][22]
(:49:42): [nss] [setup_client_idle_timer] (0x4000): Idle timer re-set for client [0x557af16f31b0][22]
(:50:12): [nss] [setup_client_idle_timer] (0x4000): Idle timer re-set for client [0x557af16f31b0][22]
(:50:42): [nss] [client_idle_handler] (0x2000): Terminating idle client [0x557af16f31b0][22]
```

Author: alexey-tikhonov

src/responder/common/responder_common.c

@@ -653,7 +653,7 @@ static void client_idle_handler(struct tevent_context *ev,
         goto done;
     }
 
-    if ((now - cctx->last_request_time) > cctx->rctx->client_idle_timeout) {
+    if ((now - cctx->last_request_time) >= cctx->rctx->client_idle_timeout) {
         /* This connection is idle. Terminate it */
         DEBUG(SSSDBG_TRACE_INTERNAL,
               "Terminating idle client [%p][%d]\n",
@@ -678,7 +678,7 @@ errno_t reset_client_idle_timer(struct cli_ctx *cctx)
 static errno_t setup_client_idle_timer(struct cli_ctx *cctx)
 {
     struct timeval tv =
-            tevent_timeval_current_ofs(cctx->rctx->client_idle_timeout/2, 0);
+            tevent_timeval_current_ofs(cctx->rctx->client_idle_timeout/2 + 1, 0);
 
     talloc_zfree(cctx->idle);