refactor: Improve AllocateTokens

[alexanderbez]

Description

Closes: #13520

Note, this is NOT SM breaking. Just a minor perf improvement to not do the same math over and over again.

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Author Checklist

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please add links to any relevant follow up issues.

I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[codecov]

Codecov Report

Merging #13524 (ade23cd) into main (4014953) will increase coverage by 0.13%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13524      +/-   ##
==========================================
+ Coverage   53.78%   53.92%   +0.13%     
==========================================
  Files         653      643      -10     
  Lines       56830    55475    -1355     
==========================================
- Hits        30567    29915     -652     
+ Misses      23819    23156     -663     
+ Partials     2444     2404      -40     

Impacted Files	Coverage Δ
x/distribution/keeper/allocation.go	90.78% <100.00%> (+0.93%)	⬆️
simapp/app.go
simapp/upgrades.go
simapp/state.go
simapp/simd/cmd/root.go
simapp/test_helpers.go
simapp/simd/cmd/testnet.go
simapp/genesis.go
simapp/simd/cmd/genaccounts.go
simapp/genesis_account.go
... and 3 more

[julienrbrt]

lgtm