We want a key that can filter on only local server builds. We need a way to make this key only applied on local server builds. Using Scons itself is an easy vector as it controls the invocations to bazel, however long term we need a way to only add this BES key even when using the bazel interface directly.

Alternatively we can do a feature request to engflow, to do "not" filter so we could filter on everything "not" evergreen CI.