increase disk quota to hold more old versions

(cherry picked from commit 34c4a406cd45107415297fb665a92b416985455d)
diff --git a/ci/images/google-geode-builder/packer.json b/ci/images/google-geode-builder/packer.json
index 8f691fd..111b8ae 100644
--- a/ci/images/google-geode-builder/packer.json
+++ b/ci/images/google-geode-builder/packer.json
@@ -16,6 +16,7 @@
       "zone": "us-central1-f",
       "image_family": "{{user `pipeline_prefix`}}linux-geode-builder",
       "image_name": "{{user `hashed_pipeline_prefix`}}gb-{{timestamp}}",
+      "disk_size": "100",
       "tags": ["packer"],
       "labels": {
         "time-to-live": "{{user `packer_ttl`}}",