[Backport] Stabilize Travis CI integration tests suite

[mageprince]

Original Pull Request

#16909

Description

Travis CI integration test suites for 2.3-develop branch are frequently failing with timeout on integration batch 2. This is caused by incorrect distribution of the tests across suites, where suite 1 runs for just 11 minutes, and suite 2 runs for up to 50 minutes.

This Pull Request changes this distribution to spread execution time more evenly between batches 1, 2 and 3.

Reference build result: https://travis-ci.org/ishakhsuvarov/magento2/builds/405247843

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[osrecio]

@mageprince Thanks for your Backport.

@ishakhsuvarov You think that this PR is applied to 2.1-develop if is only for distribution of the tests suites of branch 2.3-develop ?

[sidolov]

Hi @mageprince , this changes was addressed to 2.3 release line only and not applicable for 2.1 release line. I'm closing this PR as not relevant.