cloud: Bump archival RAM to (the max of) 8GB

Bump the RAM allocated to the data archival cloud function from 4GB to
8GB, so we avoid aborting on out-of-memory when transferring 12 hours
of data at a time.

It could be that BigQuery is accumulating memory use over time and
running out, despite us calling gc.collect() after every transfer, but I
don't have the time to pursue this further.

kcidb/cloud/functions.sh

@@ -181,7 +181,7 @@ function functions_deploy() {
                     archive true \
                     --env-vars-file "$env_yaml_file" \
                     --trigger-topic "${archive_trigger_topic}" \
-                    --memory 4096MB \
+                    --memory 8192MB \
                     --max-instances=1 \
                     --timeout 540