Increase the accuracy of rewards by minting based on the real reward.

[murisi]

Describe your changes

This PR is an attempt to slightly mitigate #4372 by reducing the amount of unclaimable rewards created by the rewards algorithm. The approach taken is to try and reduce the amount of NAM minted for non-native tokens so that it's closer to what can actually be claimed. And this reduction is achieved by minting NAM based on the deflated rewards for non-native tokens (which is what is actually put into the allowed conversions) rather than the inflated rewards they are based on. Because clients can combine (deflated) reward NAM[0] with pre-existing NAM[0] in their balance to meet the threshold for conversion to the current epoch and because the distribution algorithm now works with deflated amounts, it no longer ignores the dust arising during the mint amount computations.

To see the impact of this PR, note that the dust left at the MASP address after all shielded tokens are unshielded in https://github.com/anoma/namada/pull/4369/files#diff-78668f42dcc983dea532ff370112f41796cfae99510ea10156df37c4e1e4e0d2L2285 has gone down from nam: 0.003216 to nam: 0.000012.

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes
• If this PR requires changes to the docs or specs, a corresponding PR is opened in the namada-docs repo
  • Relevant PR if applies:
• If this PR affects services such as namada-indexer or namada-masp-indexer, a corresponding PR is opened in that repo
  • Relevant PR if applies:

[codecov]

Codecov Report

Attention: Patch coverage is 96.36364% with 2 lines in your changes missing coverage. Please review.

Project coverage is 74.53%. Comparing base (f037759) to head (d413757).
Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/shielded_token/src/conversion.rs	96.36%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4369   +/-   ##
=======================================
  Coverage   74.53%   74.53%           
=======================================
  Files         339      339           
  Lines      110504   110524   +20     
=======================================
+ Hits        82359    82377   +18     
- Misses      28145    28147    +2     

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