drop deprecated authentication_public_key from pool config

[arvidn]

Purpose:

As the TODO-comment explains:

TODO: remove this a few versions after 1.3, since authentication_public_key is deprecated. This is here to support
downgrading to versions older than 1.3.

I think it's safe to remove this. I discovered this as the current implementation of this backwards-compatibility also is not working right. It causes the _periodically_update_pool_state_task to run continuously. The reason is that calling add_auth_key() loads and re-saves the config file, thus bumping its "mtime". We use the mtime to determine whether ewe need to run this task early, rather than waiting the 60 secons we are supposed to.

Running the task calls add_auth_key() resulting in continuously running the task, wasting CPU and disk I/O.

This is especially apparent when you have multiple plotnfts.

Current Behavior:

When having many plotnfts, the farmer process pegs the CPU every 2 seconds. See the profile attached below.

New Behavior:

Having many plotnfts only causes the farmer process to perform the expensive work every 60 seconds. (There's still room for improvements in this regard, but this patch covers 95% of the problems).

Testing Notes:

I profiled the farmer process, depending on #17953

profile:

[github-actions]

File	Coverage	Missing Lines
chia/pools/pool_config.py	76.9%	lines 91, 98-99

Total	Missing	Coverage
14 lines	3 lines	78%

[coveralls-official]

Pull Request Test Coverage Report for Build 8935153853

Details

• 11 of 14 (78.57%) changed or added relevant lines in 2 files are covered.
• 42 unchanged lines in 10 files lost coverage.
• Overall coverage decreased (-0.006%) to 90.68%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
chia/pools/pool_config.py	10	13	76.92%

Files with Coverage Reduction	New Missed Lines	%
chia/harvester/harvester_api.py	1	73.02%
chia/full_node/full_node_api.py	1	80.92%
chia/rpc/rpc_server.py	1	89.0%
chia/wallet/util/wallet_sync_utils.py	1	86.54%
chia/data_layer/data_layer.py	2	85.26%
chia/data_layer/data_layer_wallet.py	2	91.26%
chia/wallet/wallet_node.py	4	88.46%
chia/server/node_discovery.py	4	79.96%
chia/full_node/full_node.py	4	85.19%
chia/_tests/core/util/test_lockfile.py	22	77.73%

Totals
Change from base Build 8931619722:	-0.006%
Covered Lines:	97989
Relevant Lines:	108007

---

💛 - Coveralls

[altendky]

sounds like this might fix the config load spam i've seen and reported a few times... but never made time to dig into. that'd be awesome. :] thanks

[emlowe]

"remove this a few versions after 1.3" - yea I guess we can do that :-)