libprefetch: Increase default fd count to 1024

Maximum capacity of 128 fds for replaying pack file
found to be too small. increasing it to 1024 should
be safe for most devices.

Bug: 380766679
Test: Builds
Test: run on devices, observe no performance regression
Change-Id: I4ee818dd5a9eb87b1a852c616ebda1bf5813d0da