Cleanup in gen_l10n files

[shihaohong]

• Fixes [gen_l10n] Recommended intl package version in the generated comment is not correct #53125, which suggests an unnecessary dependency on intl_translation: 0.17.7
• Fixes the version of intl that is recommended
• Fixes typo in option for untranslated message file reporting in printed report
• Removes ignored lints since they are no longer applicable in the main _localizations Dart file

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[HansMuller]

LGTM