ABFS: Test testNegativeScenariosForCreateOverwriteDisabled fails for non-HNS account

Test testNegativeScenariosForCreateOverwriteDisabled fails when run against a non-HNS account. The test creates a mock AbfsClient to mimic negative scenarios.

Mock is triggered for valid values that come in for permission and umask while creating a file. Permission and umask get defaulted to null values with driver when creating a file for a nonHNS account. The mock trigger was not enabled for these null parameters.