feat: (unsuccessful) upgrade to 3.11 gatling-gradle and project future 💔

[kkulak]

Description

Follow-up to the PR #120: the change introduces backward compatible upgrade to the gatling-gradle plugin 3.11+. IMHO we should simply support 3.11 syntax and make it clear, that starting from gatling-operator release x.y.z, only gradle plugin 3.11+ is supported, but I've encountered a much bigger problem while doing the upgrade 😭

gatling-operator expect that Gatling can accept gatling.core.directory.results param, but starting from version 3.11, it's not supported at all, without any alternatives:

• 3.10 supported params
• 3.11+ supported params

Probably we can deal with this problem somehow, but then I checked out what "features" are introduced by 3.12.x Gatling upgrade 😡 It has turned out that they intentionally dropped support for combing the results from multiple runs into one aggregated report, on which gatling-operator depends on. Please check out:

• https://stackoverflow.com/questions/78981709/how-to-combine-gatling-reports-from-multiple-machines
• Gatling 3.12.0 problems with multiple logs and reportsOnly option gatling/gatling#4591
• https://community.gatling.io/t/missing-command-line-options-in-gatling-3-11-bundles/9311

It seems that Gatling authors want to encourage the community to use Gatling Enterprise instead 😞

For us, it means that report aggregation & upload doesn't work anymore, and it can't be fixed. Report aggregation and remote upload are the main reasons people use gatling-operator, so I started wondering what the future holds for this project 💔

I hope I made a mistake somewhere @kane8n - please check it out carefully and come back to me, please.

Checklist

• Tests have been added (if applicable, ie. when operator codes are added or modified)
• Relevant docs have been added or modified (if applicable, ie. when new features are added or current features are modified)

Related issues:

• Gatling 3.11 upgrade #120