Remove storage snapshot functions

[ferranbt]

Description

This PR removes the Snapshot functions from the storage which have been long deprecated as far as I can understand.

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Breaking changes

Please complete this section if any breaking changes have been made, otherwise delete it

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the relevant labels
• I have updated the official documentation
• I have added sufficient documentation in code

Testing

• I have tested this code with the official test suite
• I have tested this code manually

Manual tests

Please complete this section if you ran manual tests for this functionality, otherwise delete it

Documentation update

Please link the documentation update PR in this section if it's present, otherwise delete it

Additional comments

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[codecov]

Codecov Report

Merging #830 (f179513) into develop (46a988b) will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #830      +/-   ##
===========================================
+ Coverage    52.58%   52.59%   +0.01%     
===========================================
  Files          132      132              
  Lines        17523    17523              
===========================================
+ Hits          9214     9217       +3     
+ Misses        7637     7635       -2     
+ Partials       672      671       -1     

Impacted Files	Coverage Δ
syncer/client.go	63.20% <0.00%> (+1.41%)	⬆️

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[Kourin1996]

Thank you for creating a PR even for small stuff