CLOUDP-281384: Bump OLM to v0.31.0 (#4080)

OLM was pinned to a specific version when OLM release v0.29.0 was
broken. We can now bump the version.

We can unpin it completely and always install latests, but I think it is
better to keep pinned.

Author: m1kola

scripts/dev/contexts/root-context

@@ -91,5 +91,4 @@ export OM_BASE_URL=https://cloud-qa.mongodb.com
 export e2e_cloud_qa_baseurl="${OM_HOST}"
 export e2e_cloud_qa_baseurl_static_2="${OM_HOST}"
 
-# see CLOUDP-281384
-export OLM_VERSION=v0.28.0
+export OLM_VERSION=v0.31.0