Remove unnecessary early exit in EVM::call

[yperbasis]

Because after EIP-161 it's impossible within EVM to differentiate between empty and non-existent accounts, the early exit in EVM::call is unnecessary. Its purpose was to cater for this rule of EIP-161: "No account may change state from non-existent to existent-but-empty. If an operation would do this, the account SHALL instead remain non-existent."

Without the early exit some empty accounts might be created, but then they will be deleted at transaction's end as empty touched accounts.

[codecov]

Codecov Report

Merging #632 (3ec3fe4) into master (d52bc6c) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #632      +/-   ##
==========================================
- Coverage   82.18%   82.12%   -0.07%     
==========================================
  Files         173      173              
  Lines       14433    14425       -8     
==========================================
- Hits        11862    11846      -16     
- Misses       2571     2579       +8     

Impacted Files	Coverage Δ
core/silkworm/execution/evm.cpp	95.27% <100.00%> (-0.89%)	⬇️
core/silkworm/consensus/base/engine.cpp	93.03% <0.00%> (-1.00%)	⬇️
core/silkworm/state/in_memory_state.cpp	94.14% <0.00%> (-0.98%)	⬇️

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[chfast]

Without the early exit some empty accounts might be created, but then they will be deleted at transaction's end as empty touched accounts.

I understand this depends on newly created accounts being marked as "touched".

[yperbasis]

I understand this depends on newly created accounts being marked as "touched".

Yes, that's right.