Remove requirement to target security branches

This removes the requirement and any mention of targeting security
branches when working on security releases. The release process
documentation changes for these CE changes can be found in merge request
https://gitlab.com/gitlab-org/release/docs/merge_requests/97.

The proposal to remove security branches was approved in
https://gitlab.com/gitlab-org/release/framework/issues/165#note_138139016.

.gitlab/issue_templates/Security developer workflow.md

@@ -20,10 +20,9 @@ Set the title to: `Description of the original issue`
 - [ ] Once the MR is ready to be merged, create MRs targetting the last 3 releases, plus the current RC if between the 7th and 22nd of the month.
     - [ ] At this point, it might be easy to squash the commits from the MR into one
     - You can use the script `bin/secpick` instead of the following steps, to help you cherry-picking. See the [secpick documentation]
-    - [ ] Create the branch `security-X-Y` from `X-Y-stable` if it doesn't exist (and make sure it's up to date with stable)
-    - [ ] Create each MR targetting the security branch `security-X-Y`
-    - [ ] Add the ~security label and prefix with the version `WIP: [X.Y]` the title of the MR
-- [ ] Add the ~"Merge into Security" label to all of the MRs.
+    - [ ] Create each MR targetting the stable branch `stable-X-Y`, using the "Security Release" merge request template.
+    - Every merge request will have its own set of TODOs, so make sure to
+      complete those.
 - [ ] Make sure all MRs have a link in the [links section](#links)
 
 [secpick documentation]: https://gitlab.com/gitlab-org/release/docs/blob/master/general/security/developer.md#secpick-script

.gitlab/merge_request_templates/Security Release.md

@@ -4,6 +4,9 @@ This MR should be created on `dev.gitlab.org`.
 
 See [the general developer security release guidelines](https://gitlab.com/gitlab-org/release/docs/blob/master/general/security/developer.md).
 
+This merge request _must not_ close the corresponding security issue _unless_ it
+targets master.
+
 -->
 ## Related issues
 
@@ -12,7 +15,7 @@ See [the general developer security release guidelines](https://gitlab.com/gitla
 ## Developer checklist
 
 - [ ] Link to the developer security workflow issue on `dev.gitlab.org`
-- [ ] MR targets `master` or `security-X-Y` for backports
+- [ ] MR targets `master`, or `stable-X-Y` for backports
 - [ ] Milestone is set for the version this MR applies to
 - [ ] Title of this MR is the same as for all backports
 - [ ] A [CHANGELOG entry](https://docs.gitlab.com/ee/development/changelog.html) is added without a `merge_request` value, with `type` set to `security`
@@ -25,4 +28,4 @@ See [the general developer security release guidelines](https://gitlab.com/gitla
 - [ ] Correct milestone is applied and the title is matching across all backports
 - [ ] Assigned to `@gitlab-release-tools-bot` with passing CI pipelines
 
-/label ~security ~"Merge into Security"
+/label ~security

bin/secpick

@@ -10,6 +10,7 @@ using Rainbow
 
 module Secpick
   BRANCH_PREFIX = 'security'.freeze
+  STABLE_PREFIX = 'stable'.freeze
   DEFAULT_REMOTE = 'dev'.freeze
   NEW_MR_URL = 'https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/new'.freeze
 
@@ -36,16 +37,16 @@ module Secpick
       branch.freeze
     end
 
-    def security_branch
-      "#{BRANCH_PREFIX}-#{@options[:version]}".tap do |name|
+    def stable_branch
+      "#{STABLE_PREFIX}-#{@options[:version]}".tap do |name|
         name << "-ee" if ee?
       end.freeze
     end
 
     def git_commands
-      ["git fetch #{@options[:remote]} #{security_branch}",
-       "git checkout #{security_branch}",
-       "git pull #{@options[:remote]} #{security_branch}",
+      ["git fetch #{@options[:remote]} #{stable_branch}",
+       "git checkout #{stable_branch}",
+       "git pull #{@options[:remote]} #{stable_branch}",
        "git checkout -B #{source_branch}",
        "git cherry-pick #{@options[:sha]}",
        "git push #{@options[:remote]} #{source_branch}",
@@ -56,9 +57,8 @@ module Secpick
       {
         merge_request: {
           source_branch: source_branch,
-          target_branch: security_branch,
-          title: "[#{@options[:version].tr('-', '.')}] ",
-          description: '/label ~security ~"Merge into Security"'
+          target_branch: stable_branch,
+          description: '/label ~security'
         }
       }
     end