You're going to have to fake it. What I do in situations like this is create a property with a getter and setter, but where the setter can only be used in tests.

As an example, setup a new property:

public static Integer runningJobCount{
    get{
        if(runningJobCount == null)
            return [Select count() FROM AsyncApexJob WHERE JobType='BatchApex' AND(Status = 'Processing' OR Status = 'Preparing')];
        else
            return runningJobCount;
    }
    set{
        System.assert(Test.isRunningTest(),'This property may only be set in tests');
        runningJobCount = val;
    }
}

Then change this line:

    if([Select count() FROM AsyncApexJob WHERE JobType='BatchApex' AND(Status = 'Processing' OR Status = 'Preparing')]<5){

to

    if(runningJobCount <5){
        

Then in your test you can set Schedule_Batch.runningJobCount = 5; in the test you want to test this scenario.

You're going to have to fake it. What I do in situations like this is create a property with a getter and setter, but where the setter can only be used in tests.

As an example, setup a new property:

public static Integer runningJobCount{
    get{
        if(runningJobCount == null)
            return [Select count() FROM AsyncApexJob WHERE JobType='BatchApex' AND(Status = 'Processing' OR Status = 'Preparing')];
        else
            return runningJobCount;
    }
    set{
        System.assert(Test.isRunningTest(),'This property may only be set in tests');
        runningJobCount = value;
    }
}

Then change this line:

    if([Select count() FROM AsyncApexJob WHERE JobType='BatchApex' AND(Status = 'Processing' OR Status = 'Preparing')]<5){

to

    if(runningJobCount <5){
        

Then in your test you can set Schedule_Batch.runningJobCount = 5; in the test you want to test this scenario.