Update dnf.py metric_computation function

[ltoribiosc]

The update makes the feature sort galaxies faster.

Problem & Solution Description (including issue #)

Code Quality

• My code follows the code style of this project
• I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.55%. Comparing base (0776e57) to head (a99237d).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #11   +/-   ##
=======================================
  Coverage   99.55%   99.55%           
=======================================
  Files           1        1           
  Lines         223      227    +4     
=======================================
+ Hits          222      226    +4     
  Misses          1        1           

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[hangqianjun]

Looks good! Thanks!