FeatureCompactor::compactRow always expects alphadecimal ids

Having these non-scalar values (UUID objects) was actually breaking
FlowPopulateLinksTables.php

Bug: 65083
Change-Id: I664427444688090ec2a703554b6f61a902f0b86f
(cherry picked from commit 1cce5905eecbe6ad5a9009f6c546c4c54bb1f0bd)
Merge "FeatureCompactor::compactRow always expects alphadecimal ids" into wmf/1.24wmf4