[Enhancement] @EnableDubboConfigBinding annotates @Repeatable

[mercyblitz]

@Repeatable should be annotated @EnableDubboConfigBinding .

[cvictory]

I think we can add this annotation at both 2.7.x version.
@repeatable is effcient after jdk1.8.

[mercyblitz]

@cvictory it both works Dubbo 2.6.x and 2.7.x, and may do later