[API] Snapshot delete operation flag added

[hyunsooda]

Proposed changes

This update introduces a dedicated flag, allowing the rewind of a chain specifically triggered by an explicit API call. In the current setHead functionality, deleting the snapshot database around one epoch could be time-consuming (5-10 minutes per epoch on the Cypress network with a 604800 epoch value). The new flag addresses this by selectively deleting the snapshot database only when the call path originates from an explicit API call, not degrading the user experience and potential operator frustration during instantiation.

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