Ensure refresh and refresh_db both work in aptpkg

[Ch3LL]

What does this PR do?

We do not actually want to deprecate refresh_db to ensure users to not have to update their states. This PR is removing the deprecation warning and updating the docs to urge users to user the preferred argument.

What issues does this PR fix or reference?

#49418

Previous Behavior

deprecation warning when using refresh_db

New Behavior

deprecation warning removed and docs added

Tests written?

No

Commits signed with GPG?

Yes

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@8d8e4cf). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master   #55643   +/-   ##
=========================================
  Coverage          ?    38.9%           
=========================================
  Files             ?     1467           
  Lines             ?   260318           
  Branches          ?    56410           
=========================================
  Hits              ?   101238           
  Misses            ?   147980           
  Partials          ?    11100

Flag	Coverage Δ
#macosxmojave	37.48% <ø> (?)
#py2	37.48% <ø> (?)
#py3	37.81% <ø> (?)
#runtests	38.9% <ø> (?)
#ubuntu1804	37.81% <ø> (?)
#zeromq	38.9% <ø> (?)

Impacted Files	Coverage Δ
salt/modules/aptpkg.py	44.4% <ø> (ø)
salt/states/pkgrepo.py	7.74% <ø> (ø)