fix(login): ensure css is served (#10894)

# Which Problems Are Solved

The newest release (v4.3.2) was not serving the `zitadel.css` for the
login anymore. The previous file was served from cache, making it not
directly visible.
The problem was caused due to the CI change (#10571) where the generate
was moved from a makefile to Nx commands, which run in parallel.
Depending on timing, the generated css file might be embedded into the
login or not.

# How the Problems Are Solved

- Configure the commands to run sequentially.

# Additional Changes

none

# Additional Context

- relates to #10571 
- requires backport to v4.x

apps/api/project.json

@@ -301,7 +301,8 @@
                     "PATH=\"${PWD}/.artifacts/bin/$(go env GOOS)/$(go env GOARCH):$PATH\" go generate internal/api/ui/login/statik/generate.go",
                     "PATH=\"${PWD}/.artifacts/bin/$(go env GOOS)/$(go env GOARCH):$PATH\" go generate internal/notification/statik/generate.go",
                     "PATH=\"${PWD}/.artifacts/bin/$(go env GOOS)/$(go env GOARCH):$PATH\" go generate internal/statik/generate.go"
-                ]
+                ],
+                "parallel": false
             },
             "cache": true,
             "inputs": [
@@ -456,4 +457,4 @@
             ]
         }
     }
-}
+}