Set runtime readahead to 128KiB

Reduce readahead to 128KiB to reduce thrashing under memory pressure.

Bug: 110908295
Bug: 111855179
Test: Boot
Change-Id: I449d2733bc836ed7661653efb2400fc031a76644
(cherry picked from commit bed30a438faf4e9c4eabc51edf86ef1a97d00385)
1 file changed