minsev: Update to use sdk/log.FilterProcessor

[pellared]

Fixes #6822

Update after open-telemetry/opentelemetry-go#6317

I also updated the example a little bid.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.1%. Comparing base (4b3d45d) to head (1c28d9d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #6833     +/-   ##
=======================================
- Coverage   76.1%   76.1%   -0.1%     
=======================================
  Files        219     219             
  Lines      21313   21313             
=======================================
- Hits       16224   16221      -3     
- Misses      4529    4531      +2     
- Partials     560     561      +1     

Files with missing lines	Coverage Δ
processors/minsev/minsev.go	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes