Setting negative RamWeigher

Since we will not have exact match in Icehouse, this is what gets
it closer to exact match. Negative RamWeigher causes scheduler
to pick nodes with less RAM first, so in our case it will pick
what is closest to flavors we use.

Partial-Bug: #1291396
Change-Id: I9e910bbb82b2ab456ed15af4dee2b67491d6e24b
Merge "Setting negative RamWeigher"