fix: removed deprecated sdk.DBBackend variable

[deepto98]

Description

Closes: #11410
#11241

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Author Checklist

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• confirmed the correct type prefix in the PR title
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[alexanderbez]

Let's add a changelog for this.

[tac0turtle]

LGTM, looks to be a few more stragglers of DBBackened still existing

[deepto98]

Let's add a changelog for this.

Okay, will do.

[alexanderbez]

Let's add a changelog for this.

Okay, will do.

TYSM. Also, great work 👍

[deepto98]

@alexanderbez I've removed the other occurences I could find of types.DBBackend and also added a changelog.

[codecov]

Codecov Report

Merging #12355 (9dff262) into main (69d8fa2) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #12355      +/-   ##
==========================================
- Coverage   65.57%   65.55%   -0.03%     
==========================================
  Files         685      685              
  Lines       71638    71634       -4     
==========================================
- Hits        46976    46957      -19     
- Misses      22013    22030      +17     
+ Partials     2649     2647       -2     

Impacted Files	Coverage Δ
types/utils.go	79.10% <ø> (+3.04%)	⬆️
x/distribution/simulation/operations.go	80.85% <0.00%> (-9.58%)	⬇️