refactor: date-limit has_pending_interim queries

[jennifer-richards]

Adds a date limit to the queries in the has_pending_interim() helper.

Restyles the imports in meeting/views.py because I couldn't bear to add another import without cleaning that up. The only change is to import the new PENDING_INTERIM_MAX_LOOKBACK constant.

[codecov]

Codecov Report

��� All modified and coverable lines are covered by tests.
✅ Project coverage is 88.73%. Comparing base (88cb3bf) to head (2d8c577).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #11659   +/-   ##
=======================================
  Coverage   88.73%   88.73%           
=======================================
  Files         337      337           
  Lines       45313    45338   +25     
=======================================
+ Hits        40209    40232   +23     
- Misses       5104     5106    +2     

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