Encapsulate logic scattered in CircleCI Yaml file into script files

[castelblanque]

Description:

Encapsulate logic scattered in CircleCI Yaml file into script files (e.g. cluster creation) in order to ease the future transition to Github.

• Benefit: Having all the logic of E2E execution in proper script files instead of the current mix of code embedded in yaml and other code in script files.

Related to #4096

[ppbaena]

To be closed when migrating to GitHub actions

[beni0888]

This has been mostly achieved in #4436 I keep the issue open to take a second look and see if we still can move some parts to scripts.