Defragmentation utils should use a direct connection to shards to check the feature flag

The defragmentation util includes a check for whether the NoMoreAutosplitter feature flag is enabled. This check uses the feature flag utils which check both the feature flag value and the FCV (to make sure the feature flag is enabled on the version the node is actually running).

The current check in the defragmentation utils calls the the feature flag util with a connection to the mongos. Mongos have no FCV, therefore the feature flag library is not taking into account the FCV currently running.

We should amend the check to use a direct connection so that the feature flag util can correctly check the feature flag. We should also add in a comment or a check to the feature flag util to make sure callers are aware that the util should not be used from a mongos.