Merge branch '356069-deprecate-iteration-deletion' into 'master'

Deprecate deleting iterations via the GraphQL API

See merge request gitlab-org/gitlab!83483

doc/api/graphql/reference/index.md

@@ -3236,6 +3236,10 @@ Input type: `iterationCreateInput`
 
 ### `Mutation.iterationDelete`
 
+WARNING:
+**Deprecated** in 14.10.
+Manual iteration management is deprecated. Only automatic iteration cadences will be supported in the future.
+
 Input type: `IterationDeleteInput`
 
 #### Arguments

ee/app/graphql/ee/types/deprecated_mutations.rb

@@ -5,7 +5,11 @@ module EE
     module DeprecatedMutations
       extend ActiveSupport::Concern
 
+      ITERATION_DEPRECATION_MESSAGE = 'Manual iteration management is deprecated. Only automatic iteration cadences will be supported in the future'
+
       prepended do
+        mount_mutation ::Mutations::Iterations::Delete,
+          deprecated: { reason: ITERATION_DEPRECATION_MESSAGE, milestone: '14.10' }
         mount_aliased_mutation 'CreateIteration', ::Mutations::Iterations::Create,
           deprecated: { reason: 'Use iterationCreate', milestone: '14.0' }
       end

ee/app/graphql/ee/types/mutation_type.rb

@@ -23,7 +23,6 @@ module EE
         mount_mutation ::Mutations::Projects::SetLocked
         mount_mutation ::Mutations::Iterations::Create
         mount_mutation ::Mutations::Iterations::Update
-        mount_mutation ::Mutations::Iterations::Delete
         mount_mutation ::Mutations::Iterations::Cadences::Create
         mount_mutation ::Mutations::Iterations::Cadences::Update
         mount_mutation ::Mutations::Iterations::Cadences::Destroy