Remove Sqlite backend

[yzang2019]

Describe your changes and provide context

Remove SQLITE backend from ss store since we do not plan to support it and we have never used that before.

Testing performed to validate your change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 40.06%. Comparing base (c3ee918) to head (bd1e80c).
⚠️ Report is 3 commits behind head on main.

❌ Your project status has failed because the head coverage (40.06%) is below the target coverage (60.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #121      +/-   ##
==========================================
+ Coverage   40.00%   40.06%   +0.06%     
==========================================
  Files          59       59              
  Lines        7510     7533      +23     
==========================================
+ Hits         3004     3018      +14     
- Misses       4161     4168       +7     
- Partials      345      347       +2     

Files with missing lines	Coverage Δ
ss/store.go	50.00% <ø> (+2.11%)	⬆️

... and 2 files with indirect coverage changes

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[masih]

Late to the party but this LGTM, thank you for actioning this so quickly @yzang2019 🍻