[CHIA-1357] Correctly set start_index in create_more_puzzle_hashes

[Quexington]

Due to a logic error, start_index in the create_more_puzzle_hashes function would always be set to 0 resulting in the re-derivation of potentially many pubkeys that were not necessary. This PR correctly creates the intended variable of lowest_start_index.

[emlowe]

@arvidn This was introduced here #17991
I have a little trouble following the logic a bit, so please review

[wjblanke]

aok!

[coveralls-official]

Pull Request Test Coverage Report for Build 10780640914

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 49 unchanged lines in 11 files lost coverage.
• Overall coverage decreased (-0.01%) to 90.895%

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Files with Coverage Reduction	New Missed Lines	%
chia/wallet/util/wallet_sync_utils.py	1	86.54%
chia/timelord/timelord_launcher.py	1	69.34%
chia/full_node/weight_proof.py	2	90.66%
chia/farmer/farmer_api.py	2	94.39%
chia/server/node_discovery.py	3	80.32%
chia/server/server.py	4	82.21%
chia/server/address_manager.py	7	90.48%
chia/timelord/timelord.py	7	80.71%
chia/farmer/farmer.py	7	72.39%
chia/daemon/server.py	7	83.33%

Totals
Change from base Build 10777346322:	-0.01%
Covered Lines:	101571
Relevant Lines:	111706

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💛 - Coveralls