This is a follow-up for #176 .

Client's PR brave/brave-core#20329 sends in HistoryDeleteDirectiveSpecifics in un-encrypted way.

Server should remove entries by HistoryDeleteDirectiveSpecifics::global_id_directive::global_id converted to client_hash_tag or by HistoryDeleteDirectiveSpecifics::time_range_directive.

When this issue will be resolved, syncer::LowPriorityUserTypes override at client must be reverted.
cc @yrliou , @DJAndries