Remove array of runtimes

[ferranbt]

Description

This PR removes the list of runtimes that the state transition can use and defaults to evm and precompiles. Initially, it was envisioned that the client could have different runtimes to execute transitions (evm, wasm,?). However, at this point, I am not sure that idea has solidified in something tangible. Thus, this PR removes that complexity and simplifies the code. This can be introduced later if the need for new runtimes appears again.

Changes include

• Bugfix (non-breaking change that solves an issue)
• Hotfix (change that solves an urgent issue, and requires immediate attention)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)

Breaking changes

Please complete this section if any breaking changes have been made, otherwise delete it

Checklist

• I have assigned this PR to myself
• I have added at least 1 reviewer
• I have added the relevant labels
• I have updated the official documentation
• I have added sufficient documentation in code

Testing

• I have tested this code with the official test suite
• I have tested this code manually

Manual tests

Please complete this section if you ran manual tests for this functionality, otherwise delete it

Documentation update

Please link the documentation update PR in this section if it's present, otherwise delete it

Additional comments

Please post additional comments in this section if you have them, otherwise delete it

[codecov]

Codecov Report

Merging #859 (f688d60) into develop (417a4be) will increase coverage by 0.33%.
The diff coverage is 39.74%.

@@             Coverage Diff             @@
##           develop     #859      +/-   ##
===========================================
+ Coverage    52.58%   52.91%   +0.33%     
===========================================
  Files          132      128       -4     
  Lines        17523    17268     -255     
===========================================
- Hits          9214     9137      -77     
+ Misses        7637     7469     -168     
+ Partials       672      662      -10     

Impacted Files	Coverage Δ
chain/chain.go	23.34% <ø> (-5.35%)	⬇️
consensus/ibft/ibft.go	1.62% <0.00%> (+0.01%)	⬆️
network/config.go	100.00% <ø> (ø)
network/e2e_testing.go	63.76% <ø> (-0.14%)	⬇️
network/identity/identity.go	18.94% <0.00%> (+0.58%)	⬆️
network/server_discovery.go	74.53% <0.00%> (ø)
state/executor.go	3.89% <0.00%> (+0.03%)	⬆️
network/server.go	74.89% <55.55%> (-0.48%)	⬇️
network/server_identity.go	94.11% <100.00%> (-0.14%)	⬇️
syncer/client.go	63.20% <100.00%> (+1.41%)	⬆️
... and 5 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more