[FEATURE] Use paratest for composer script

[Starkmann]

This needs to be done for runTests.sh as well

Part of #1379

[coveralls]

Pull Request Test Coverage Report for Build 10162255986

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 10161996152:	0.0%
Covered Lines:	46
Relevant Lines:	46

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💛 - Coveralls

[Starkmann]

With parallel execution we have a race condition between functional test since they all are running on the same database:

Duplicate entry '1' for key 'tx_tea_domain_model_tea.PRIMARY'

[oliverklee]

@Starkmann This PR still has an open review comment.