Reused CoinsViewOverlay layered on top of m_cacheview and passed to ConnectBlock(). Reset between calls and flushed only on success, so invalid blocks don't pollute the underlying cache.
Declared in <validation.h>
[[guarded_by(0x7f2e1b986f98), guarded_by(0x7f2e275ffe68), guarded_by(0x7f2e372f0e48), guarded_by(0x7f2e2b182ed8)]]
std::unique_ptr<CoinsViewOverlay> m_connect_block_view;