[archivist] Reduce number of threads

Change-Id: I77c7d27cc6d0af88468bbf4e12dc1909d66f86dd
diff --git a/src/diagnostics/archivist/configs.gni b/src/diagnostics/archivist/configs.gni
index dfc01b4b..00ba45e 100644
--- a/src/diagnostics/archivist/configs.gni
+++ b/src/diagnostics/archivist/configs.gni
@@ -19,7 +19,7 @@
   listen_to_lifecycle = true
   log_to_debuglog = true
   logs_max_cached_original_bytes = 4194304
-  num_threads = 4
+  num_threads = 2
   pipelines_path = "/config/data"
 }