HPCC-9078 The default system will not start on a 32-bit VM with 10 GB memory

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>

This change preven to crash Thor component on a 32 bit environment when
more than 2 GB physical RAM exits.

Originally the condition was more than 4GB, but in 32 bit OS environment
only 3 GB or less memory can use by application.
Merge branch 'HPCC-9078-fix' into candidate-4.0.0

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>