random_mounts=false incorrectly attempts to enable new mount on existing path

- Intended Behavior (when random_mounts is true): If the random_mounts flag is set to true, the tool correctly creates a brand new kvv2 or auth engine during the test setup. This is expected.
- Problematic Behavior (when random_mounts is false): When the random_mounts flag is set to false, users expect the tool to utilize an already existing mount specified in the config.hcl file. However, the tool incorrectly tries to enable a new mount at that specified path during the setup phase.
- Why this is an issue: The purpose of disabling random_mounts and providing an existing path is to allow tool to configure roles, policies, or seeding secrets on an already established mount, not to create a duplicate or new mount where one already exists.

Start by tracing the setup path that handles random_mounts and the existing mount path from config.hcl. Done means random_mounts=false reuses the configured existing mount without attempting to enable a new one, while random_mounts=true continues creating a new kvv2 or auth engine.

Written by the indexing model from the issue text.