Update localizable string identifier to correctly show lower 7-days stats comparison (#20000)

Author: staskus

WordPress/Classes/ViewRelated/Stats/Insights/StatsTotalInsightsCell.swift

@@ -379,7 +379,7 @@ class StatsTotalInsightsCell: StatsBaseCell {
         static let differenceHigher = NSLocalizedString("stats.insights.label.totalLikes.higher",
                                                         value: "*%@%@ (%@%%)* higher than the previous 7-days",
                                                         comment: "Label shown on some metrics in the Stats Insights section, such as Comments count. The placeholders will be populated with a change and a percentage – e.g. '+17 (40%) higher than the previous 7-days'. The *s mark the numerical values, which will be highlighted differently from the rest of the text.")
-        static let differenceLower = NSLocalizedString("stats.insights.label.totalLikes.higher",
+        static let differenceLower = NSLocalizedString("stats.insights.label.totalLikes.lower",
                                                        value: "*%@%@ (%@%%)* lower than the previous 7-days",
                                                        comment: "Label shown on some metrics in the Stats Insights section, such as Comments count. The placeholders will be populated with a change and a percentage – e.g. '-17 (40%) lower than the previous 7-days'. The *s mark the numerical values, which will be highlighted differently from the rest of the text.")
         static let differenceSame = NSLocalizedString("stats.insights.label.totalLikes.same",