Don't init WP_Locale_Switcher in wp_load_translations_early()

[ocean90]

See ticket:29783:59.

WP_Locale_Switcher uses get_locale()/get_user_locale() to set the original locale. Both functions can return a fatal error if WordPress isn't fully initialized. [38976] tries to fix this but in a bad way. wp_load_translations_early() sets the locale based on various factors like WPLANG or $wp_local_package. [38976] assumes that it's always en_US.

I'm not aware of a use case where someone would need to switch locales while the site is crashing. I'm proposing to revert [38976] and [38977] and to remove WP_Locale_Switcher from wp_load_translations_early().

Related: #30049

[ocean90]

In 39005:

I18N: Don't initialize WP_Locale_Switcher in wp_load_translations_early().

wp_load_translations_early() is used when WordPress isn't fully initialized. Therefore using the WP_Locale_Switcher with get_locale()/get_user_locale() can cause PHP fatal errors.
This reverts [38976] and [38977], and instead removes WP_Locale_Switcher from wp_load_translations_early().

See #29783.
Fixes #38535.

[ocean90]

In 39130:

Load: Remove unused global imports in wp_load_translations_early().

See #38535.