Remove trailing zeroes in tax amount

[Naokimi]

Summary

Issue
amount_for_adjustment_label uses ActiveSupport::NumberHelper::NumberToPercentageConverter which defaults to a precision of 3, leading to the tax amount displayed in the label in a way that isn't very pleasing:

Proposed Solution
Use amount's default precision

Checklist

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[waiting-for-dev]

@Naokimi, could you please rebase from master to fix CI errors? 🙏

[waiting-for-dev]

Thanks! ❤️

[codecov]

Codecov Report

Merging #4758 (5483bc1) into master (efe2b3a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4758   +/-   ##
=======================================
  Coverage   86.14%   86.14%           
=======================================
  Files         578      578           
  Lines       14654    14654           
=======================================
  Hits        12623    12623           
  Misses       2031     2031           

Impacted Files	Coverage Δ
core/app/models/spree/tax_rate.rb	100.00% <ø> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[github-actions]

💔 Some backports could not be created

Status	Branch	Result
✅	v3.2
❌	v3.1	Backport failed because of merge conflicts

Manual backport

To create the backport manually run:

backport --pr 4758

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details

[github-actions]

💔 Some backports could not be created

Status	Branch	Result
✅	v3.2
❌	v3.1	Backport failed because of merge conflicts

Manual backport

To create the backport manually run:

backport --pr 4758

Questions ?

Please refer to the Backport tool documentation and see the Github Action logs for details

[waiting-for-dev]

@Naokimi, could you please manually backport it to v3.1? The automatic backporting failed because of merge conflicts 🙏

[tvdeyen]

This now adds a trailing zero to all VAT tax rates in ie. German stores, but we want no precision at all so we used the locale file to set the format.

# de.yml
de:
  number:
    percentage:
      format:
        precision: 0

Now we cannot control the format with locale files anymore.
The preposed solution should have been to set:

# en.yml
en:
  number:
    percentage:
      format:
        precision: 1

in the config/locales/en.yml file of your app.

Can we please revert this? @solidusio/core-team

[tvdeyen]

Revert PR #4824

[tvdeyen]

I added a commit to #4824 that changes the default precision of EN stores to 1 (instead of the Rails default of 3). This should fix what this PR tried to fix for all EN based stores.