chore(circleci): update cache paths (open-telemetry#640)

Author: mayurkale22

.circleci/config.yml

@@ -71,7 +71,8 @@ cache_2: &cache_2
     - packages/opentelemetry-plugin-https/node_modules
     - packages/opentelemetry-plugin-postgres/opentelemetry-plugin-pg-pool/node_modules
     - packages/opentelemetry-plugin-mysql/node_modules
-    - packages/opentelemetry-exporter-prometheus/node_modules
+    - packages/opentelemetry-exporter-collector/node_modules
+    - packages/opentelemetry-plugin-xml-http-request/node_modules
 
 node_unit_tests: &node_unit_tests
   steps: