Adds numHosts to hosts retrieval for proper pagination

numHosts was suppressed in an earlier commit but this caused
issues with pagination of results.

scripts/lua/do_export_data.lua

@@ -29,6 +29,7 @@ else
    -- All hosts
    
    hosts_stats = interface.getHostsInfo()
+   hosts_stats = hosts_stats["hosts"]
    num = 0
    print("[\n")
 
@@ -49,4 +50,4 @@ else
 
    print("\n]\n")
 end
-end
+end