14f16748557faf57cf4b0f4c91c162592557434c chainparams: add mainnet assumeutxo param at height 880_000 (Sjors Provoost)
Pull request description:
#31940 suggests adding a snapshot at every major release.
This snapshot should be suitable for v29. I picked the most recent multiple of 10K blocks.
You can either download this torrent:
```
magnet:?xt=urn:btih:559bd78170502971e15e97d7572e4c824f033492&dn=utxo-880000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969
```
Or generate the snapshot yourself:
```sh
bitcoin-cli -rpcclienttimeout=0 -named dumptxoutset utxo-880000.dat rollback=880000
```
The SHA-256 hash should be:
```
shasum -a 256 utxo-880000.dat
43b3b1ad6e1005ffc0ff49514d0ffcc3e3ce671cc8d02da7fa7bac5405f89de4
```
And then load it on a fresh node during IBD with:
```
bitcoin-cli -rpcclienttimeout=0 loadtxoutset utxo-880000.dat
```
Note that it's more performant to turn off networking while the snapshot is loading, see #29993:
```sh
bitcoin-cli setnetworkactive false
```
Once the snapshot is loaded:
```sh
bitcoin-cli setnetworkactive true
```
And enjoy a speedy ride to the tip.
ACKs for top commit:
achow101:
ACK 14f16748557faf57cf4b0f4c91c162592557434c
fjahr:
tACK 14f16748557faf57cf4b0f4c91c162592557434c
hodlinator:
ACK 14f16748557faf57cf4b0f4c91c162592557434c
rkrux:
Concept ACK 14f16748557faf57cf4b0f4c91c162592557434c
polespinasa:
ACK 14f1674855
Tree-SHA512: e7ed3e8ce3a247614545ecd3254a91814d7f87b3ca1be46df3b9a4c1e6353b46c82ab97d9fc9c5bed8938f28a6a61e6b70baa7c9649fe5da0f2f390b7932f15e
e13c18f6ce