Exclude EasyConfigs from --from-pr builds

[Flamefire]

It would be great to exclude particular easyconfigs when doing --from-pr, e.g. all belonging to Intel/2017 for which we don't have a license.

Using only specified ECs is possible, but cumbersome when you want to build 16 and exclude 2 from 18 total.

So maybe: --include-ec-regex and --exclude-ec-regex?

[boegel]

@Flamefire This can be closed, thanks to the support for --filter-ecs which was implemented in #3796 ?

[Flamefire]

Yes