[BUG] Overriding DAB lookup variables in targets breaks variables view

[jamuska]

Describe the bug
When you define a lookup variable in databricks.yml and override it with another value under some target, Bundle variables view does not show variable values.

To Reproduce
Steps to reproduce the behavior:

1. Init new bundle databricks bundle init default-python
2. Define variables in databricks.yml

variables: 
  test: test_value
  lookup_test:
    lookup: 
      service_principal: test_service_principal

3. Override lookup_test under dev target

targets:
  dev:
    variables:
      lookup_test:
        lookup:
          service_principal: override_service_principal

4. Bundle variables view becomes empty

Screenshots
Without overridden lookup variable

After overriding lookup variable

System information:

1. Paste the output ot the Help: About command (CMD-Shift-P).
   Version: 1.94.2 (user setup)
   Commit: 384ff7382de624fb94dbaf6da11977bba1ecd427
   Date: 2024-10-09T16:08:44.566Z
   Electron: 30.5.1
   ElectronBuildId: 10262041
   Chromium: 124.0.6367.243
   Node.js: 20.16.0
   V8: 12.4.254.20-electron.0
   OS: Windows_NT x64 10.0.22631
2. Databricks Extension Version
   2.4.7
   Databricks Extension Logs
   Please attach the databricks extension logs
   I cannot get Open Full logs from command palette to work when running vscode with WSL remote. I will try to add these later.

Additional context
Add any other context about the problem here.

[jamuska]

Side note: the link to instructions for attaching extension logs is broken. The instructions are under this page https://docs.databricks.com/en/dev-tools/vscode-ext/troubleshooting.html