Improve performance of IceCat PIM integration

On large catalogs 350K+ IceCat index processing job takes too long, going into 6h+.

Need to revise the DailyIndexProcessorImpl in order to assess how this can be reduces to a reasonable amount of time. Acceptable levels are ~3h (4h max) in order to achieve daily refresh without affecting daily auto imports of catalogs.

This task should be reviewed in conjunction with XML import work in YC-941