Optimization: CreateAccount only clears state if code hash exists

[stevenlanders]

Describe your changes and provide context

• when an account is created by evm, it needs to clear out any existing contract state
• clearing / deleting is expensive, so it makes sense to try to early-bail if possible
• the new logic only clears if the code hash key is set

Testing performed to validate your change

• perf analysis on pacific-1 rpc node
• fixed unit tests that were not setting code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.09%. Comparing base (b16814c) to head (30bd1de).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2255      +/-   ##
==========================================
- Coverage   60.12%   60.09%   -0.04%     
==========================================
  Files         309      309              
  Lines       29995    30029      +34     
==========================================
+ Hits        18035    18045      +10     
- Misses      10685    10707      +22     
- Partials     1275     1277       +2     

Files with missing lines	Coverage Δ
x/evm/state/state.go	97.91% <100.00%> (+2.17%)	⬆️

... and 3 files with indirect coverage changes

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