fix the bug not setting iavl-cache-size value of app.toml

[zemyblue]

Description

Fix the bug not setting iavl-cache-size value of app.toml of simapp

And change DefaultIAVLCacheSize to 1024 * 512.
Because the iavl cache size is just one store's iavl cache size and each modules have itself's store. if the all module's store use iavl type, the default all iavl cache size is very big. So I change default size to a little small size.

related: #666, #675

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov]

Codecov Report

Merging #679 (fc4d807) into main (80ba750) will increase coverage by 0.03%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #679      +/-   ##
==========================================
+ Coverage   61.06%   61.10%   +0.03%     
==========================================
  Files         873      873              
  Lines       98601    98602       +1     
==========================================
+ Hits        60215    60253      +38     
+ Misses      34781    34732      -49     
- Partials     3605     3617      +12     

Impacted Files	Coverage Δ
server/config/toml.go	20.00% <ø> (ø)
store/iavl/store.go	68.29% <ø> (ø)
simapp/simd/cmd/root.go	81.73% <100.00%> (+0.07%)	⬆️
x/foundation/msgs.go	42.78% <0.00%> (-1.93%)	⬇️
x/token/msgs.go	32.99% <0.00%> (+0.50%)	⬆️
x/foundation/foundation.go	76.17% <0.00%> (+1.44%)	⬆️
crypto/keys/internal/ecdsa/privkey.go	84.21% <0.00%> (+1.75%)	⬆️
x/collection/msgs.go	42.40% <0.00%> (+6.48%)	⬆️

[ulbqb]

LGTM