Clean-up removed metric

The metric for the GitLab slack application was removed and marked
as ignored - this change updates the metrics files to reflect this
fact.

config/metrics/counts_7d/20210916102312_templates_gitlab_slack_application_active.yml

@@ -7,8 +7,9 @@ product_stage: ecosystem
 product_group: group::integrations
 product_category: integrations
 value_type: number
-status: active
+status: removed
 milestone: "14.3"
+milestone_removed: "14.4"
 introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/70496
 time_frame: 7d
 data_source: database

ee/spec/config/metrics/every_metric_definition_spec.rb

@@ -17,7 +17,7 @@ RSpec.describe 'Every metric definition' do
   let(:usage_ping_key_paths) do
     parse_usage_ping_keys(usage_ping)
       .flatten
-      .reject { |v| v =~ Regexp.union(ignored_usage_ping_key_patterns) }
+      .grep_v(Regexp.union(ignored_usage_ping_key_patterns))
       .sort
   end
 
@@ -27,7 +27,6 @@ RSpec.describe 'Every metric definition' do
       mock_ci
       mock_monitoring
       user_auth_by_provider
-      templates_gitlab_slack_application_active
       p_ci_templates_5_min_production_app
       p_ci_templates_aws_cf_deploy_ec2
       p_ci_templates_auto_devops_build