Breaking: #79243 - Remove sys_language_softMergeIfNotBlank

See Issue #79243

Description

The TypoScript setting config.sys_language_softMergeIfNotBlank has been removed without any replacement. This is a result of removing the TCA setting mergeIfNotBlank from the list of possible values for l10n_mode.

Migration

Remove TypoScript setting config.sys_language_softMergeIfNotBlank.