Clang-format IntegerLiteralSeparator too strict

[JVApen]

When using IntegerLiteralSeparator with a Decimal digit separator at '3', you get a digit separator once your integer has a 4th digit.
However, consider the following case:

auto today = std::chrono::year_month_day{2023, 3, 6};

due to this guideline, it gets transformed into:

auto today = std::chrono::year_month_day{2'023, 3, 6};

Although correct according to the configuration, it does not improve the readability of that code.
Would it be possible to next to Decimal have an option MinDigitDecimal which is used to check if we have sufficient digits before this transformation is needed? For the value 5, it would require 10'000, though not 1'000.

[llvmbot]

@llvm/issue-subscribers-clang-format

[owenca]

https://reviews.llvm.org/D147111

[owenca]

/cherry-pick 5b5c49a 253985d

[llvmbot]

/branch llvm/llvm-project-release-prs/issue61209