fixed no screenshots on passed cases allure

[kobenguyent]

By this reported #1494 I found out that:

• The screenshot to attach to allure for failed test cases is already handled in screenshotOnFail.js

        const allureReporter = Container.plugins('allure');
        if (allureReporter) {
          allureReporter.addAttachment('Last Seen Screenshot', fs.readFileSync(path.join(global.output_dir, fileName)), 'image/png');
        }

so, we don't need to handle it again in stepByStepReport.js

    const allureReporter = Container.plugins('allure');
    if (allureReporter && (step.status !== 'success')) {
      output.plugin('stepByStepReport', 'Adding screenshot to Allure');
      allureReporter.addAttachment('Screenshot', fs.readFileSync(path.join(dir, fileName)), 'image/png');
    }

this will lead to

• duplicate screenshots on allure reports.
• screenshot will be added to passed cases on allure reports.

[DavertMik]

Ok, but If I want step-by-step reports for allure?

[kobenguyent]

then I think this PR is not needed.

[kobenguyent]

But still there are a lot of screenshots are attached to allure

[DavertMik]

Can we bring this as a config option?

[kobenguyent]

I‘ll check it out.

[kobenguyent]

Now when the screenshotsForAllureReport is set to true, you will see something like this

[DavertMik]

Thanks!