BHV-8481: Use delegate pattern for FlyweightRepeater.

Issue
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There was an interim fix for `FlyweightRepeater` that relied on testing whether or not the control was overloading the given generator method.

Fix
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Use the new delegate pattern for `FlyweightRepeater`.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>