Migrate project selectors away from select2

What does this MR do and why?

This migrate the remaining select2-based project selector inputs to the new ProjectSelect Vue component.

Screenshots or screen recordings

Group insights project setting

Before	After

Instance templates project setting

Before	After

Cluster management project setting

Before	After

Analytics Dashboards project setting

Before	After

How to set up and validate locally

• Group insights project setting
  • Navigate to a group's Settings > General > Insights setting (/groups/:group/-/edit).
• Instance templates project setting
  • Navigate to Admin > Settings > Templates > Templates setting (/admin/application_settings/templates).
• Cluster management project setting
  • Enable the certificate_based_clusters feature flag:

    Feature.enable(:certificate_based_clusters)

  • Create a cluster in the Admin > Kubernetes page (dummy values can be used).
  • Short-circuit the condition in the HAML view by applying the following patch (I'm not sure how to access the setting without this bypass):

    diff --git a/app/views/clusters/clusters/_advanced_settings.html.haml b/app/views/clusters/clusters/_advanced_settings.html.haml
    index ddc3b7d05e1b..8e0289d91191 100644
    --- a/app/views/clusters/clusters/_advanced_settings.html.haml
    +++ b/app/views/clusters/clusters/_advanced_settings.html.haml
    @@ -4,7 +4,7 @@
       - group_id = @cluster.project.group.id if @cluster.project.group
       - user_id = @cluster.project.namespace.owner_id unless group_id
     
    -- if can?(current_user, :admin_cluster, @cluster)
    +- if true
       - unless @cluster.provided_by_user?
         .sub-section.form-group
           %h4

  • Navigate to Admin > Kubernetes > :cluster > Advanced Setting > Cluster management project settings (/admin/clusters/1?tab=settings).
• Analytics Dashboards project setting
  • Short-circuit the condition in the HAML view by applying the following patch (I'm not sure how to access the setting without this bypass):

    diff --git a/ee/app/views/groups/_analytics_dashboards.html.haml b/ee/app/views/groups/_analytics_dashboards.html.haml
    index 7b823543c475..3f7331c3be2f 100644
    --- a/ee/app/views/groups/_analytics_dashboards.html.haml
    +++ b/ee/app/views/groups/_analytics_dashboards.html.haml
    @@ -1,4 +1,4 @@
    -- return unless can?(current_user, :read_group_analytics_dashboards, @group)
    +-# - return unless can?(current_user, :read_group_analytics_dashboards, @group)
     
     %section.settings.analytics-dashboards-settings.no-animate{ class: ('expanded' if expanded) }
       .settings-header

  • Navigate to a group's Settings > General > Analytics Dashboards setting (/groups/:group/-/edit).

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #374098 (closed)