This is a backport of [[https://github.com/bitcoin/bitcoin/pull/16378 | core#16378]] [3/3]
https://github.com/bitcoin/bitcoin/pull/16378/commits/92326d89766155a792254d30a9962251b8fc7799
Depends on D10264
Backport differences:
- Arguments `conf_target` and `estimate_mode`, as well as the options of the same name are removed. The option `fee_rate` can be used to set the fee. The `RPCExamples` are updated accordingly.
- Options `change_type` and `replaceable` are removed.
- The functional test sets the fee rate with `fee_rate` option, so the unit is XEC/kB instead of sat/B.
- In the test, I did not set `decimal.getcontext().prec = 2`, because this causes a suprising loss of precision that makes somes checks fail:
```
>>> from decimal import getcontext, Decimal
>>> getcontext().prec = 2
>>> Decimal("1329999995.50") - Decimal("1328999993.25")
Decimal('1.0E+6')
```