Remove Tekton Dashboard from edp-tekton chart

[daniil-nedostup]

Is your feature request related to a problem? Please describe.
The edp-install chart currently includes the field edp-tekton.dashboard in its values.yaml file, which is intended to override the dashboard configuration in the edp-tekton chart. However, the edp-tekton chart no longer supports this field because the Tekton Dashboard is no longer part of its scope. Keeping this field in edp-install can confuse users and lead to misconfigurations.

Describe the solution you'd like
Remove the edp-tekton.dashboard field from the values.yaml file of the edp-install chart. Update the documentation and any related references to reflect this change and ensure users are informed about the updated configuration.

Describe alternatives you've considered
Retain the edp-tekton.dashboard field with a warning in the documentation that it is no longer functional.

Additional context
Ensure the Helm chart’s CI/CD pipelines are updated to validate the removal.