Selectively cherry pick EnhancedKeyLoader changes from the 0.59 release to the 0.58 release

[nathanklick]

Description

In the release/0.58 branch, the EnhancedKeyLoader still uses the AddressBookUtils.isLocal() method for identifying which private keys should be present. The release/0.59 branch uses the -local cli switch and/or the nodesToRun environment variable to determine which private keys must be present on disk.

The above logic in release/0.59 needs to be cherry picked back to the release/0.58 branch. This is required to support multi-cluster deployments with overlapping internal IP ranges.