[Proofpoint TAP] Clarify state restoration log to “last ingestion run attempt”

[Copilot]

The Proofpoint TAP connector logs last_campaign_datetime as “last ingested,” which is misleading because the value represents the timestamp from the previous ingestion run attempt. This update aligns log wording with actual connector behavior.

• Log semantics

  • Updated connector INFO log in state restoration path from:
    • Connector last ingested {state_key} datetime
  • to:
    • Connector last ingestion run attempt {state_key}

• Regression coverage

  • Added a focused unit test asserting _initiate_work() emits the updated message with last_campaign_datetime metadata when state is present.

self._logger.info(
    f"[CONNECTOR] Connector last ingestion run attempt {state_key}",
    {state_key: last_ingested_datetime_str},
)