Chore: Remove nonsense function update_rule_group_interval

[amotl]

About

Remove function update_rule_group_interval as suggested by @vbichov.

• update_rule_group_interval and update_rule_group have the same functionality  #204

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.33%. Comparing base (717f203) to head (48c5434).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #207      +/-   ##
==========================================
+ Coverage   92.29%   92.33%   +0.04%     
==========================================
  Files          27       27              
  Lines        1816     1814       -2     
==========================================
- Hits         1676     1675       -1     
+ Misses        140      139       -1     

Flag	Coverage Δ
unittests	92.33% <ø> (+0.04%)	⬆️

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