fix: existing account number increment on each callback

[freeelancer]

Description

Currently each time IBCReceivePacketCallback it will trigger acc = k.authKeeper.NewAccountWithAddress(ctx, receiver) then k.authKeeper.SetAccount(ctx, acc). This causes the account number to change which is unexpected behavior.

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Author Checklist

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I have...

• tackled an existing issue or discussed with a team member
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• targeted the main branch

[aljo242]

thank you for opening this @freeelancer - can you add some tests for this?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.63%. Comparing base (4a67ba7) to head (e5993b1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #970      +/-   ##
==========================================
+ Coverage   65.57%   65.63%   +0.06%     
==========================================
  Files         319      319              
  Lines       22220    22221       +1     
==========================================
+ Hits        14571    14585      +14     
+ Misses       6480     6474       -6     
+ Partials     1169     1162       -7     

Files with missing lines	Coverage Δ
x/ibc/callbacks/keeper/keeper.go	70.58% <100.00%> (+0.21%)	⬆️

... and 2 files with indirect coverage changes

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[vladjdk]

@freeelancer Can you please add an issue and associate this PR with it?