OSPF standard says that intra-area prefixes are preferred over inter-area prefixes independent of the metrics/costs, so you cannot do anything about it. Route preference can be modified for internal and external OSPF routes but both inter-/intra-area routes are both internal.
Won't help you much but one way to solve this issue would be to run multiple adjacencies between R2 and R5, i.e. make this link part of area 0 and area 30 at the same time and thus the path R5-R2-R1-R3-R4 intra-area as well. Actually there is a standard for OSPF multiarea adjacencies (RFC 5185), but this is only supported on MX series router and not on SRX.
Cheers,
Carsten