[BUG] Simulator fails when support bundle generated in standalone mode lacks the node folder

Description:

When using the support bundle kit in standalone mode using the sample manifest file, the generated support bundle does not include a node folder. This happens because node collection is not triggered in that file. The following environment variables are set in the YAML triggers the node collection:

- name: SUPPORT_BUNDLE_NODE_SELECTOR
  value: ""
- name: SUPPORT_BUNDLE_TAINT_TOLERATION
  value: ":"
- name: SUPPORT_BUNDLE_NODE_TIMEOUT
  value: 30m0s

The Bug:

Whether the standalone generation results doesn't have a node folder, running the simulator on this bundle fails because it strictly expects the node directory to exist.

Error Message

FATA[0022] Error loading node zip objects error during dir walk: lstat /support-bundles/nodes: no such file or directory 

Steps to Reproduce:

1. Generate a support bundle using standalone mode with the sample manifest file.
2. Attempt to run the simulator against the generated bundle.
3. The simulator fails due to the missing node folder.

Workaround:

As a quick fix you can do the following,

• Update the sample manifest file with above node collection triggering environment variables.
• Manually creating an empty node/ folder inside the bundle allows the simulator to run successfully.

Proposed Solution:

The simulator should be updated to gracefully handle bundles that do not contain a node folder (or have an empty one), as this is expected behavior for certain environments and standalone configurations.

Next Steps:

Please let me know whether this is indeed a correct issue. If it is, I will proceed with creating a PR that updates the simulator to ignore the node folder if it is missing.