loadBannerAd looping because of autoRefresh

[FujiKinaga]

Will be called onAdLoaded() or onAdFailedToLoad(int errorCode) of AdListener when AdMob's autoRefresh do.
So I guess that we should make AdListener into null on first callback.

Current

Improved

I want to know whether we should refresh all adList or only visible ad when auto refreshing any ad.
Or do you have some better solutions? ex. On RecyclerView's viewHolder.onBindViewHolder, start loading and prefetch next indexed ad. (my sample)

Could you please give me some feedbacks!🙇‍♂️

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[FujiKinaga]

@googlebot I signed it!

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