[CHIA-1427]: Limit full file creation when processing subscription generations

[emlowe]

When syncing a subscription, DL downloads the delta files for each generation as it walks all the singleton generations. Currently each time it will also write out a full file - however, that full file isn't used and will be eventually deleted as the default is to only keep on full file.

This PR is an attempt to limit creating the full files except when we are within the range where we should generate the full files.

It will also create a full file if a delta file fails to download entirely - this makes sure that if in the middle of processing the deltas the code happens to be unable to move forward, a full file will get generated at that point.

[coveralls-official]

Pull Request Test Coverage Report for Build 10966220826

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

• 23 of 23 (100.0%) changed or added relevant lines in 3 files are covered.
• 25 unchanged lines in 8 files lost coverage.
• Overall coverage decreased (-0.003%) to 90.97%

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Files with Coverage Reduction	New Missed Lines	%
chia/full_node/full_node_api.py	1	82.36%
chia/wallet/wallet_node.py	1	88.37%
chia/daemon/client.py	1	73.94%
chia/_tests/core/util/test_file_keyring_synchronization.py	1	97.14%
chia/full_node/full_node.py	4	86.7%
chia/server/server.py	4	82.21%
chia/server/node_discovery.py	6	79.26%
chia/server/address_manager.py	7	90.48%

Totals
Change from base Build 10949495080:	-0.003%
Covered Lines:	102032
Relevant Lines:	112126

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💛 - Coveralls

[altendky]

Seems like a good change to me. I put in a few code form comments, but I'm not strongly attached to them.

[altendky]

comments are being considered separately for potential refactoring later