Problem: memiavl setup code is not clean

[yihuang]

👮🏻👮🏻👮🏻 !!!! REFERENCE THE PROBLEM YOUR ARE SOLVING IN THE PR TITLE AND DESCRIBE YOUR SOLUTION HERE !!!! DO NOT FORGET !!!! 👮🏻👮🏻👮🏻

PR Checklist:

• Have you read the CONTRIBUTING.md?
• Does your PR follow the C4 patch requirements?
• Have you rebased your work on top of the latest master?
• Have you checked your code compiles? (make)
• Have you included tests for any non-trivial functionality?
• Have you checked your code passes the unit tests? (make test)
• Have you checked your code formatting is correct? (go fmt)
• Have you checked your basic code style is fine? (golangci-lint run)
• If you added any dependencies, have you checked they do not contain any known vulnerabilities? (go list -json -m all | nancy sleuth)
• If your changes affect the client infrastructure, have you run the integration test?
• If your changes affect public APIs, does your PR follow the C4 evolution of public contracts?
• If your code changes public APIs, have you incremented the crate version numbers and documented your changes in the CHANGELOG.md?
• If you are contributing for the first time, please read the agreement in CONTRIBUTING.md now and add a comment to this pull request stating that your PR is in accordance with the Developer's Certificate of Origin.

Thank you for your code, it's appreciated! :)

[codecov]

Codecov Report

Merging #994 (7748e31) into master (836309b) will decrease coverage by 0.11%.
The diff coverage is 100.00%.

❗ Current head 7748e31 differs from pull request most recent head 3484cfc. Consider uploading reports for the commit 3484cfc to get more accurate results

@@            Coverage Diff             @@
##           master     #994      +/-   ##
==========================================
- Coverage   33.16%   33.06%   -0.11%     
==========================================
  Files         128      126       -2     
  Lines       20029    19999      -30     
==========================================
- Hits         6642     6612      -30     
  Misses      12329    12329              
  Partials     1058     1058              

Flag	Coverage Δ
integration_tests	20.68% <100.00%> (-0.10%)	⬇️
integration_tests_byzantine	9.62% <100.00%> (-0.06%)	⬇️
integration_tests_gov	9.95% <100.00%> (-0.14%)	⬇️
integration_tests_grpc	9.93% <100.00%> (-0.14%)	⬇️
integration_tests_ibc	24.76% <100.00%> (-0.01%)	⬇️
integration_tests_ledger	9.82% <100.00%> (-0.04%)	⬇️
integration_tests_slow	9.82% <100.00%> (-0.04%)	⬇️
integration_tests_solomachine	9.62% <100.00%> (-0.04%)	⬇️
integration_tests_upgrade	9.93% <100.00%> (-0.14%)	⬇️
unit_tests	10.97% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
app/app.go	91.78% <100.00%> (ø)
cmd/chain-maind/app/app.go	83.52% <100.00%> (ø)