Make conditional matrix jobs easier to define

[pweyck]

Make conditional matrix executions easier to define. It should be possible to define an action that does this.

We already use dynamic matrices in some places, but it's always a custom script. We should be able cover most cases with a simple generic solution.

Use this to implement this: https://shopware-ag.slack.com/archives/C02UA3UL2LA/p1739962843426339

[philipreinken]

Mostly in regards to the ATS not running for major feature set (https://github.com/shopware/shopware/blob/trunk/.github/workflows/integration.yml#L37):

Might not be necessary to run these, however PHP integration tests should be executed with FEATURE_ALL=major on a regular basis.