Match ktlint_code_style with Ktlint documentation

[Jaehwa-Noh]

Ktlint document says that

Starting from version 1.0, ktlint_official is the default code style. If you want to revert to another code style, then set the .editorconfig property ktlint_code_style.

But Spotless default set intellij_idea It makes developer mistake and misconception.

According Ktlint documentation, only one want to revert another code style must set the ktlint_code_style, but in Spotless need to set the ktlint_code_style who want to apply ktlint_official or else styles.

diffplug#2090