tests: do not check for Solution UI deployment

Since the UI is optionnal and we no longer deploy
it from the Solution framework, we do not want to
check for its presence as it's not directly related
to the Solution framework anymore.
Plus, this test would break because the Example
Solution has not been adapted yet to deploy its
UI.

Refs: #2581

tests/post/features/solutions.feature

@@ -17,7 +17,6 @@ Feature: Solutions
         When we remove Taints on node 'bootstrap' before deployment
         And we deploy Solution 'example-solution' in environment 'example-environment' with version '0.1.0-dev'
         Then we have 1 running pod labeled 'app=example-solution-operator' in namespace 'example-environment'
-        And we have 1 running pod labeled 'app=example-solution-ui' in namespace 'example-environment'
         When we deactivate Solution 'example-solution'
         And we delete Solution 'example-solution' in environment 'example-environment'
         And we delete Solution environment 'example-environment'