fix: layer with shared encoding ignore repeater

[ChiaLingWeng]

close #8734

I noticed that the main reason for the spec failed to replace repeat is due to there are some problem when handling the shared layer encoding, the params.repeater will be read when running mapUnit at the first time, but since in shared layer spec, the encoding will not be at the same layer as the repeater, and the repeater will not be record since mapUnitWithParentEncodingOrProjection will return config only, and the repeat is thus cannot be replaced.

I am not familiar with typescript so using some redundant code, I think this can be clean up and be more concised.