refactor: remove useless DenomMetadata key function

[tkxkd0159]

Make DenomMetadata substore only with DenomMetadataPrefix

Description

closes: #714

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov]

Codecov Report

Merging #716 (6b88faa) into main (00ab960) will increase coverage by 0.02%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #716      +/-   ##
==========================================
+ Coverage   61.89%   61.91%   +0.02%     
==========================================
  Files         874      874              
  Lines       98638    98638              
==========================================
+ Hits        61048    61068      +20     
+ Misses      33966    33938      -28     
- Partials     3624     3632       +8     

Impacted Files	Coverage Δ
x/bank/keeper/keeper.go	73.37% <100.00%> (ø)
x/wasm/keeper/keeper.go	85.80% <0.00%> (-0.37%)	⬇️
x/collection/msgs.go	37.03% <0.00%> (+0.37%)	⬆️
x/token/msgs.go	39.08% <0.00%> (+10.65%)	⬆️

[zemyblue]

Please add changelog.

[loin3]

Changes in https://github.com/cosmos/cosmos-sdk/pull/9890/files x/bank/migrations/v043/keys.go does not reflected here.
I'm not sure about this, is it okay not reflect this?

[tkxkd0159]

Changes in https://github.com/cosmos/cosmos-sdk/pull/9890/files x/bank/migrations/v043/keys.go does not reflected here. I'm not sure about this, is it okay not reflect this?

yeah, it's legacy migration. So we don't need it (I think we need it only when we want to migrate with Upgrade without any initialize new genesis)