With `queuedTx` owning the `CTransactionRef` shared ptrs, they (and
the managed objects) are entirely allocated on the heap. In
`DisconnectedBlockTransactions::DynamicMemoryUsage`, we account for
the 2 pointers that make up the shared_ptr, but not for the managed
object (CTransaction) or the control block.
Prior to this commit, by calculating the `RecursiveDynamicUsage` on
a `CTransaction` whenever modifying `cachedInnerUsage`, we account
for the dynamic usage of the `CTransaction`, i.e. the `vins` and
`vouts` vectors, but we do not account for the `CTransaction`
object itself, nor for the `CTransactionRef` control block.
This means prior to this commit, `DynamicMemoryUsage` underestimates
dynamic memory usage by not including the `CTransaction` objects and
the shared ptr control blocks.
Fix this by calculating `RecursiveDynamicUsage` on the
`CTransactionRef` instead of the `CTransaction` whenever modifying
`cachedInnerUsage`.
In `AddTransactionsToBlock` description comment we have the asuumption
that callers will never pass multiple transactions with the same txid
We are asserting to assume that does not happen.
