The FeatureFlagUtil JS library uses the "new Mongo(...)" syntax here to create a new connection to a mongod node.

This syntax bypasses any runCommand or other JS-overrides and attempts to create a connection using the DBClientRS/DBClientConnection C++ code to back the new Mongo object. It's possible that the C++ code encounters a network error when establishing the connection. If we're using the library in an environment where such network errors are expected and should be retried, like a suite doing step-downs or kill-primaries in the background, we need to retry on these network errors.

SERVER-91008 improved the situation here but the fix only works if we got an error back from the remote server before the connection is closed that we identify as retryable; this is because it expects there to be a code on the error. WE should additionally accomodate cases where we experience the network error 'locally' - that is, the underlying connection was closed before we got a response, and we get a network error from the OS.

This can be accomplished by using isRetryableError from utils.js, or using the overriden globalThis.connect here to make the new connection.