ledger: Resolve Rust 1.88 clippy lints and format strings

[steviez]

Problem

Working towards #6850, broken out from #6854

Summary of Changes

• Run cargo clippy --fix --tests with Rust 1.88.0 set in rust-toolchain.toml
  • These should only be instances of uninlined_format_args
• Run cargo fmt with format_strings = true set in rustfmt.toml

[codecov-commenter]

Codecov Report

❌ Patch coverage is 35.81081% with 95 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.2%. Comparing base (4807a7a) to head (d5966cb).
⚠️ Report is 2932 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6964   +/-   ##
=======================================
  Coverage    83.2%    83.2%           
=======================================
  Files         856      856           
  Lines      376390   376385    -5     
=======================================
+ Hits       313281   313293   +12     
+ Misses      63109    63092   -17     

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[brooksprumo]

[cpubot]

LGTM!