VirusTotal fixes

[sc0ttes]

Proposed changes

• Add delay if connector fails to start because it can't make a connection to the OpenCTI platform (following the template's example)
• When VirusTotal connector had auto-enrichment enabled, if a large artifact file was uploaded, it took a few seconds to finish uploading to OpenCTI and propagate through the system. The VT connector would fail with a list index exception when looking for the "importFiles" list. Adding a small delay and updating the observable variable allows for that propagation time to complete before moving on with the process.

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality using different use cases
  • Tested with multiple file sizes
  • Tested with bringing services up slowly
• I added/update the relevant documentation (either on github or on notion)
• Where necessary I refactored code to improve the overall quality