refactor(sync): remove legacy sync-v1.0

[jansegre]

Motivation

It's been legacy for a while and we haven't even deployed any nodes with 1.0 support for a while.

Acceptance Criteria

• v1_1 references become v1, and v1 is removed
• sync-v1 being enabled means SyncVersion.V1_1(with value 'v1.1') is used and never SyncVersion.V1 (with value 'v1') which could previously be used depending on a cli argument
• the --x-enable-legacy-sync-v1_0 argument is removed, nothing else changes for the CLI

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (382cc38) 85.42% compared to head (07f34ee) 85.38%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #864      +/-   ##
==========================================
- Coverage   85.42%   85.38%   -0.05%     
==========================================
  Files         282      281       -1     
  Lines       22270    22231      -39     
  Branches     3367     3364       -3     
==========================================
- Hits        19025    18981      -44     
  Misses       2583     2583              
- Partials      662      667       +5     

Files	Coverage Δ
hathor/builder/builder.py	92.02% <100.00%> (+0.43%)	⬆️
hathor/builder/cli_builder.py	75.00% <100.00%> (-0.13%)	⬇️
hathor/p2p/sync_v1/factory.py	100.00% <ø> (ø)
hathor/p2p/sync_version.py	88.88% <100.00%> (-1.59%)	⬇️
hathor/p2p/states/hello.py	76.23% <0.00%> (+3.96%)	⬆️
hathor/p2p/manager.py	71.39% <50.00%> (-1.19%)	⬇️

... and 8 files with indirect coverage changes

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