fix(alienvault): strip API key whitespace and improve auth error handling

[Copilot]

Users with valid OTX keys were getting AlienVault connector internal error: 'Invalid API Key' (HTTP 403) due to accidental leading/trailing whitespace in the configured key — a common copy-paste artifact.

Changes

• client.py — call .strip() on the API key before passing it to OTXv2, neutralizing whitespace padding:

  self.otx = OTXv2(api_key.strip(), server=server)

• connector.py — catch InvalidAPIKey specifically before the generic Exception handler; log an actionable message pointing to ALIENVAULT_API_KEY and https://otx.alienvault.com/api, then sys.exit(1) to stop the connector immediately rather than retrying indefinitely with a broken credential:

  except InvalidAPIKey:
      self._error(
          "AlienVault connector authentication failed: Invalid API key. "
          "Please verify the value of ALIENVAULT_API_KEY. "
          "You can find your OTX key at https://otx.alienvault.com/api"
      )
      sys.exit(1)

  Previously the generic handler surfaced "'Invalid API Key'" (with repr() quotes) and no remediation guidance.