fix: add label(s) without success comment if successComment is false

[june21x]

Currently the successComment and releasedLabels behaviour are not decoupled. My team is currently using this and wish to label each released issue with latest release version, so that we could filter out issues based on release version on the labels when working with GitHub's Project V2 automation workflow.

However, the successComment on multiple issues will trigger a lot of emails and GitHub Teams App notifications, which we would like to turn off to avoid annoying notification spamming.

This PR removes the coupling between successComment and releasedLabels, so that user could feel free to add labels without the bot comments.

close #421

[june21x]

@gr2m Please review

[june21x]

thanks for the review @zigang93 @gr2m, I will create another clean PR for this (with updated test) soon since I noticed that I didn't follow the current Prettier rule and there were also irrelevant changes in package.json