RFR: 2316: Prefer not to specify UTF-8 if it's used by default

[Zhao Song]

On Fri, 5 Jul 2024 09:31:39 GMT, Pavel Rappo <prappo at openjdk.org> wrote:

> Please review this clean-up. It's about not specifying UTF-8 encoding when it's the default, such as in `Files.{readString, writeString}`.
> 
> The change is very uniform, except for two cases, where specifying the encoding was avoided by slightly more involved refactoring:
> 
>   * `JsonWriter:44`
>   * `XML:42`

Good to know UTF-8 encoding is default in most cases!

-------------

Marked as reviewed by zsong (Reviewer).

PR Review: https://git.openjdk.org/skara/pull/1668#pullrequestreview-2160974194