Batch1:
global class ScheduleBatchToResetKBArticleReviewer implements schedulable{
    global void execute(SchedulableContext sc){
        //Custom setting
        KBAutomatedOperations__c cSData = KBAutomatedOperations__c.getValues('Reset KBArticle Reviewer');
        System.debug('cSData----->'+cSData);
        if(cSData != null){
            //Verify whether to run batch job or not .verify whether to skin next run
            if(cSData.Active__c && !cSData.SkipNextRun__c){
                    //initialize batch class
                    BatchToResetKBArticleReviewer executeBacth = new BatchToResetKBArticleReviewer();
                    //Execute batch
                    ID batchID = Database.executeBatch(executeBacth,1);
            }
            
            CronTrigger cronKBResetReviewer = [SELECT Id, CronExpression, PreviousFireTime ,TimesTriggered, NextFireTime,CronJobDetailID,CronJobDetail.Name,State FROM CronTrigger WHERE id =: sc.getTriggerId()];
            cSData.SkipNextRun__c = false;
            cSData.Previous_Run__c = cronKBResetReviewer.PreviousFireTime;
            cSData.Next_Run__c = cronKBResetReviewer.NextFireTime;
            update cSData;      
        }       
    }//End of Method  
}//End of Class

Batch2:

global class BatchToResetKBArticleReviewer implements Database.Batchable<String>{
    global Iterable<String> start(Database.BatchableContext BC)
    {   
        String stringQuery ='Select Id, Current_Reviewer__c from ';
        String whereClause =' where PublishStatus =\'Draft\' and Language = \'en_US\' and Current_Reviewer__c != null and Article_Status__c != \'Published\'';
        
        return new List<String> { stringQuery + 'Break_Fix__Kav'+ whereClause , stringQuery + 'Tutorial__kav'+ whereClause,stringQuery + 'Tech_Alert__kav'+ whereClause,stringQuery + 'FAQ__kav'+ whereClause};
    }

    global void execute(Database.BatchableContext BC,List<String> scope){
    //create  map which have knowledgeArticleId as key and sObject as value. SObject can be of any article type[Break fix , FAQ, Tech Alert]
        Map<Id,SObject> kaIdwithArticletypeSObjectMap = new Map<Id,SObject>();
        //For each article type add key and value to map
        for(String articleTypeQuery : scope){
                kaIdwithArticletypeSObjectMap.putAll(Database.query(articleTypeQuery));
        }
        if(kaIdwithArticletypeSObjectMap.size() > 0){
            for(sobject  sObj : kaIdwithArticletypeSObjectMap.Values()){
                //set current editor with blank value
                sObj.put('Current_Reviewer__c',null);
            }
            try{        
                update kaIdwithArticletypeSObjectMap.values();
            }catch(Exception ex){
                System.debug('### System Exception : '+ex);
                SystemUtils.createApexExceptionLog(ex,'BatchToBlankKBArticleReviewer');
            }                
        }
    }
    
    global void finish(Database.BatchableContext BC){
        System.debug('@@@@@@@@@@@ FINISH METHOD @@@@@@@@@@@@@');
    }
}

For both Batches I written one test class

@isTest
public class TestScheduleBatchToResetKBArticle {

  @isTest static void ScheduleBatchToResetKB_M1(){
        
        KBAutomatedOperations__c kbsetting = new KBAutomatedOperations__c();
        kbsetting.Active__c = true;
        kbsetting.SkipNextRun__c = false;
        kbsetting.name = 'Reset KBArticle Reviewer';
        insert kbsetting;
        
        FAQ__kav testFAQ = new FAQ__kav();
        testFAQ.language = 'en_US';
        testFAQ.urlname = 'testurl1';
        //testFAQ. ValidationStatus = 'Draft';
        testFAQ.title = 'testurl1title';
        testFAQ.Current_Reviewer__c = userInfo.getUserId();
        database.insert(testFAQ);
        
        Test.startTest();
        
        //ScheduleBatchToResetKBArticleReviewer scheduleClass = new ScheduleBatchToResetKBArticleReviewer();
        //String sch = '0 0 0 * * ?';      
        //system.schedule(System.Label.KB_Reset_KBArticle_Reviewer, sch, scheduleClass);
        String CRON_EXP = '0 0 0 1 1 ? 2025';  
        String jobId = System.schedule('testScheduledApex', CRON_EXP, new ScheduleBatchToResetKBArticleReviewer() );
                 
        Test.stopTest();
        
     
        
    }  
 
    
}