TASK: Dev experience fail if e2e tests are executed without `build-e2e-testing`

[mhsdesign]

as described here, we need to use keepNames so that react magic selectors can work.

This is done only if the build is made for e2e testing, as this safes us 100Mb in the bundle:

neos-ui/esbuild.js

Line 29 in 9585ca7

keepNames: isE2ETesting, // for react magic selectors,

So without this options the e2e tests will fail locally.

So we should definitely document this more prominent and also check inside our end to end tests if this option was set to guard against unnecessary debugging and headaches ^^

Neos 8.2 and up affected

TODO

• Also it would be nice to fail when the user interface language is not correct :)

[mhsdesign]

still needs to be documented for make start-neos-dev-instance

[mhsdesign]

• also i think we have some duplicated docker code now with make start-neos-dev-instance and test-e2e-docker

[mhsdesign]

No longer required after playwright #4163