Disabling 4 VIET-specific decision files from VIso4

The following decision files are now additionally blank:

VIET_heresy_decisions.txt, VIET_misc_decisions.txt,
VIET_misc_religion_decisions.txt, VIET_West_Africa_decisions.txt

This should leave the following ones active:

VIET_Pagan_decisions, VIET_Z_Customization_Options,
realm_decisions, succession_laws
Revert "Disabling 4 VIET-specific decision files from VIso4"

This reverts commit 4132e5065e70382b9fbdf21abf50c25441f8042f.

VIso5 was CTD-free, so we now need to dig into re-enabling some combo
of these reverted decisions.
VIso6

Of the interesting 4 determined from VIso5:

Blanked:
VIET_misc_religion_decisions.txt, VIET_West_Africa_decisions.txt

Leaving these active:
VIET_heresy_decisions.txt, VIET_misc_decisions.txt
VIso7

Blanked:
VIET_heresy_decisions.txt

Active (in interesting set):
VIET_misc_decisions.txt
Merge pull request #61 from cybrxkhan/iso7

Iso7