MDL-81608 quiz: Deprecated unused lang strings

The language strings `addpagebreak` and `removepagebreak` have been
deprecated and should no longer be used.

.upgradenotes/MDL-81608-2026031009535369.yml

@@ -0,0 +1,8 @@
+issueNumber: MDL-81608
+notes:
+  mod_quiz:
+    - message: >-
+        The language strings `addpagebreak` and `removepagebreak` have been
+        deprecated and should no longer be used. These have been replaced by
+        the `addpagebreakafter` and `removepagebreakafter` language strings.
+      type: deprecated

public/mod/quiz/lang/en/deprecated.txt

@@ -1,3 +1,4 @@
+addpagebreak,mod_quiz
 attemptsdeleted,mod_quiz
 gradesdeleted,mod_quiz
 useroverridesdeleted,mod_quiz
@@ -5,5 +6,6 @@ groupoverridesdeleted,mod_quiz
 randomcoursecatwithsubcat,mod_quiz
 randomcoursewithsubcat,mod_quiz
 randomsystemwithsubcat,mod_quiz
+removepagebreak,mod_quiz
 selectquestionbank,mod_quiz
 gobacktoquiz,mod_quiz

public/mod/quiz/lang/en/quiz.php

@@ -43,7 +43,6 @@ $string['addnewgroupoverride'] = 'Add group override';
 $string['addnewpagesafterselected'] = 'Add new pages after selected questions';
 $string['addnewquestionsqbank'] = 'Add questions to the category {$a->catname}: {$a->link}';
 $string['addnewuseroverride'] = 'Add user override';
-$string['addpagebreak'] = 'Add page break';
 $string['addpagebreakafter'] = 'Add page break after question {$a}';
 $string['addpagehere'] = 'Add page here';
 $string['addquestion'] = 'Add question';
@@ -903,7 +902,6 @@ $string['removeallgroupoverrides'] = 'All group overrides';
 $string['removeallquizattempts'] = 'All quiz attempts';
 $string['removealluseroverrides'] = 'All user overrides';
 $string['removeemptypage'] = 'Remove empty page';
-$string['removepagebreak'] = 'Remove page break';
 $string['removepagebreakafter'] = 'Remove page break after question {$a}';
 $string['removeselected'] = 'Remove selected';
 $string['rename'] = 'Rename';
@@ -1170,5 +1168,7 @@ $string['randomcoursewithsubcat'] = 'Any category in this course';
 $string['randomsystemwithsubcat'] = 'Any system-level category';
 
 // Deprecated since Moodle 5.2.
+$string['addpagebreak'] = 'Add page break';
 $string['gobacktoquiz'] = 'Go back';
+$string['removepagebreak'] = 'Remove page break';
 $string['selectquestionbank'] = 'Select question bank';