Fixed the initialization of the chain simulator when working with 0-value activation epochs

[iulianpascalau]

Reasoning behind the pull request

• Chain simulator can not start with 0-value activation epochs as the epochStartSCProcessor needs to properly initialize some system smart contracts

Proposed changes

• fixed the initialization of the chain simulator when working with 0 value activation epochs by manually calling the EpochSystemSCProcessor.ProcessSystemSmartContract method on the metachain node
• added RemoveAccounts function on the chain simulator

Testing procedure

• standard system test, the main code base, although changed, is not impacted
• import-db test for the changed line in epochStart/metachain/legacySystemSCs.go

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?

[miiu96]

remove empty line before

[iulianpascalau]

done

[gabi-vuls]

Normal allin test: v1.6.15-dev-config-eb2e06c06d -> fixed-chain-simulator-zero-a32cde0cd3

--- Specific errors ---

block hash does not match 139
wrong nonce in block 114
miniblocks does not match 0
num miniblocks does not match 0
miniblock hash does not match 0
block bodies does not match 0
receipts hash missmatch 0

/------/

--- Statistics ---

Nr. of all ERRORS: 0
Nr. of all WARNS: 234
Nr. of new ERRORS: 0
Nr. of new WARNS: 6
Nr. of PANICS: 0

/------/

--- ERRORS ---

/------/

--- WARNINGS ---

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