chore: change default iavl-cache-size

[zemyblue]

Description

Change default iavl-cache-size of config.
Default real iavl cache size set 128MB.
So I set the DefaultIAVLCacheSize = 1048576.

Motivation and context

The iavl cach size of config is different with real cache size.
The config setting size is the number of iavl cache unit. And 1 iavl cache unit is 128byte struct according to cosmos/cosmos-sdk#10561 (comment)

So current default iavl cache size is so big.

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 #666 (17b59c7) into main (070ab3f) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #666      +/-   ##
==========================================
- Coverage   60.45%   60.42%   -0.04%     
==========================================
  Files         826      826              
  Lines       96128    96128              
==========================================
- Hits        58111    58082      -29     
- Misses      34514    34560      +46     
+ Partials     3503     3486      -17     

Impacted Files	Coverage Δ
server/config/toml.go	20.00% <ø> (ø)
store/iavl/store.go	68.29% <ø> (ø)
x/foundation/authz.go	80.00% <0.00%> (-20.00%)	⬇️
x/foundation/msgs.go	33.17% <0.00%> (-8.18%)	⬇️
x/collection/msgs.go	36.85% <0.00%> (-2.97%)	⬇️
x/foundation/foundation.go	72.20% <0.00%> (-1.45%)	⬇️
x/wasm/keeper/keeper.go	85.80% <0.00%> (-0.37%)	⬇️
server/config/config.go	44.92% <0.00%> (ø)
crypto/keys/internal/ecdsa/privkey.go	84.21% <0.00%> (+1.75%)	⬆️
... and 2 more