soc: esp32: decrease region 1 default pool size

Make the available heap for the 128k bank smaller
so that it frees up space for some samples
as pktqueue and smp. In the context of toolchain,
this enables having twister test to pass in those tests
that requires more memory.

Signed-off-by: Sylvio Alves <sylvio.alves@espressif.com>