Replaces #29297, descendant from #27535
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This PR removes `locals` as a concept from transaction pools. Therefore,
the pool now acts as very a good simulation/approximation of how our
peers' pools behave. What this PR does instead, is implement a
locals-tracker, which basically is a little thing which, from time to
time, asks the pool "did you forget this transaction?". If it did, the
tracker resubmits it.
If the txpool _had_ forgotten it, chances are that the peers had also
forgotten it. It will be propagated again.
Doing this change means that we can simplify the pool internals, quite a
lot.
### The semantics of `local`
Historically, there has been two features, or usecases, that has been
combined into the concept of `locals`.
1. "I want my local node to remember this transaction indefinitely, and
resubmit to the network occasionally"
2. "I want this (valid) transaction included to be top-prio for my
miner"
This PR splits these features up, let's call it `1: local` and `2:
prio`. The `prio` is not actually individual transaction, but rather a
set of `address`es to prioritize.
The attribute `local` means it will be tracked, and `prio` means it will
be prioritized by miner.
For `local`: anything transaction received via the RPC is marked as
`local`, and tracked by the tracker.
For `prio`: any transactions from this sender is included first, when
building a block. The existing commandline-flag `--txpool.locals` sets
the set of `prio` addresses.
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Co-authored-by: Gary Rong <garyrong0905@gmail.com>