Remove un-used parameter _sort_key from api.py

[UtkarshShah0]

What this PR does / why we need it: Removed un-used parameter _sort_key from delfin/db/sqlalchemy/api.py and replaced it with

Which issue this PR fixes: fixes #886

Special notes for your reviewer: SODACODE 2022

[codecov[bot]]

Codecov Report

Merging #892 (afca73b) into master (0272eed) will not change coverage. The diff coverage is 100.00%.

:exclamation: Current head afca73b differs from pull request most recent head e488242. Consider uploading reports for the commit e488242 to get more accurate results

@@           Coverage Diff           @@
##           master     #892   +/-   ##
=======================================
  Coverage   70.47%   70.47%           
=======================================
  Files         181      181           
  Lines       19055    19055           
  Branches     2812     2812           
=======================================
  Hits        13429    13429           
  Misses       4756     4756           
  Partials      870      870           

Impacted Files	Coverage Δ
delfin/db/sqlalchemy/api.py	71.91% <100.00%> (ø)

[UtkarshShah0]

@skdwriting Please review and approve. One more approval required

[anvithks]

LGTM

#SODA-PR-ACCEPTED Based on @joseph-v approval