Remove `ci_plan_needs_size_limit` feature flag

This makes 50 of DAG to be a current limit
for all.

config/feature_flags/development/ci_plan_needs_size_limit.yml

----
-name: ci_plan_needs_size_limit
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/37568
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/238173
-group: group::ci
-type: development
-default_enabled: true
\ No newline at end of file

doc/ci/yaml/README.md

@@ -2088,9 +2088,7 @@ This example creates four paths of execution:
 - The maximum number of jobs that a single job can need in the `needs:` array is limited:
   - For GitLab.com, the limit is 50. For more information, see our
     [infrastructure issue](https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/7541).
-  - For self-managed instances, the limit is:
-    - 10, if the `ci_plan_needs_size_limit` feature flag is disabled (default).
-    - 50, if the `ci_plan_needs_size_limit` feature flag is enabled. This limit [can be changed](#changing-the-needs-job-limit).
+  - For self-managed instances, the limit is: 50. This limit [can be changed](#changing-the-needs-job-limit).
 - If `needs:` refers to a job that is marked as `parallel:`.
   the current job will depend on all parallel jobs created.
 - `needs:` is similar to `dependencies:` in that it needs to use jobs from prior stages,

lib/gitlab/ci/features.rb

@@ -50,10 +50,6 @@ module Gitlab
         ::Feature.enabled?(:ci_disallow_to_create_merge_request_pipelines_in_target_project, target_project)
       end
 
-      def self.ci_plan_needs_size_limit?(project)
-        ::Feature.enabled?(:ci_plan_needs_size_limit, project, default_enabled: true)
-      end
-
       def self.lint_creates_pipeline_with_dry_run?(project)
         ::Feature.enabled?(:ci_lint_creates_pipeline_with_dry_run, project, default_enabled: true)
       end

lib/gitlab/ci/pipeline/seed/build.rb

@@ -11,8 +11,6 @@ module Gitlab
 
           delegate :dig, to: :@seed_attributes
 
-          DEFAULT_NEEDS_LIMIT = 10
-
           def initialize(pipeline, attributes, previous_stages)
             @pipeline = pipeline
             @seed_attributes = attributes
@@ -140,11 +138,7 @@ module Gitlab
           end
 
           def max_needs_allowed
-            if ::Gitlab::Ci::Features.ci_plan_needs_size_limit?(@pipeline.project)
-              @pipeline.project.actual_limits.ci_needs_size_limit
-            else
-              DEFAULT_NEEDS_LIMIT
-            end
+            @pipeline.project.actual_limits.ci_needs_size_limit
           end
 
           def pipeline_attributes

spec/lib/gitlab/ci/pipeline/seed/build_spec.rb

@@ -931,47 +931,30 @@ RSpec.describe Gitlab::Ci::Pipeline::Seed::Build do
     context 'when using 101 needs' do
       let(:needs_count) { 101 }
 
-      context 'when ci_plan_needs_size_limit is disabled' do
+      it "returns an error" do
+        expect(subject.errors).to contain_exactly(
+          "rspec: one job can only need 50 others, but you have listed 101. See needs keyword documentation for more details")
+      end
+
+      context 'when ci_needs_size_limit is set to 100' do
         before do
-          stub_feature_flags(ci_plan_needs_size_limit: false)
+          project.actual_limits.update!(ci_needs_size_limit: 100)
         end
 
         it "returns an error" do
           expect(subject.errors).to contain_exactly(
-            "rspec: one job can only need 10 others, but you have listed 101. See needs keyword documentation for more details")
+            "rspec: one job can only need 100 others, but you have listed 101. See needs keyword documentation for more details")
         end
       end
 
-      context 'when ci_plan_needs_size_limit is enabled' do
+      context 'when ci_needs_size_limit is set to 0' do
         before do
-          stub_feature_flags(ci_plan_needs_size_limit: true)
+          project.actual_limits.update!(ci_needs_size_limit: 0)
         end
 
         it "returns an error" do
           expect(subject.errors).to contain_exactly(
-            "rspec: one job can only need 50 others, but you have listed 101. See needs keyword documentation for more details")
-        end
-
-        context 'when ci_needs_size_limit is set to 100' do
-          before do
-            project.actual_limits.update!(ci_needs_size_limit: 100)
-          end
-
-          it "returns an error" do
-            expect(subject.errors).to contain_exactly(
-              "rspec: one job can only need 100 others, but you have listed 101. See needs keyword documentation for more details")
-          end
-        end
-
-        context 'when ci_needs_size_limit is set to 0' do
-          before do
-            project.actual_limits.update!(ci_needs_size_limit: 0)
-          end
-
-          it "returns an error" do
-            expect(subject.errors).to contain_exactly(
-              "rspec: one job can only need 0 others, but you have listed 101. See needs keyword documentation for more details")
-          end
+            "rspec: one job can only need 0 others, but you have listed 101. See needs keyword documentation for more details")
         end
       end
     end