Merge branch 'feature/support-8.x-with-main' into 8.x

* feature/support-8.x-with-main: (196 commits)
  support github label backport
  chore
  it should be main
  feat: bump beats to current main (elastic#14781)
  build(deps): bump github.com/elastic/elastic-agent-client/v7 from 7.16.0 to 7.17.0 (elastic#14757)
  PGO: Update default.pgo from benchmarks https://github.com/elastic/apm-server/actions/runs/12024199004/attempts/1. (elastic#14734)
  build(deps): bump slackapi/slack-github-action from 1.27.0 to 2.0.0 in the github-actions group (elastic#14656)
  build(deps): bump the otel group with 3 updates (elastic#14746)
  build(deps): bump the otel group across 1 directory with 4 updates (elastic#14681)
  testing: remove missing Make target dep (elastic#14523)
  build(deps): bump the dependencies group in /systemtest with 3 updates (elastic#14731)
  build(deps): bump chainguard/static in /packaging/docker (elastic#14732)
  build(deps): bump github.com/stretchr/testify from 1.9.0 to 1.10.0 (elastic#14733)
  chore: Update to elastic/beats@4278366ab032 (elastic#14725)
  changelog: add 8.15.5 entry (elastic#14720)
  chore: Update to elastic/beats@06ba17caf9ed (elastic#14711)
  Surface config parsing error under EA managed mode (elastic#14574)
  release-automation: update changelog template to add bug fixes section (elastic#14693)
  PGO: Update default.pgo from benchmarks https://github.com/elastic/apm-server/actions/runs/11946993444/attempts/1. (elastic#14699)
  changelog: add changelog entry for 8.16.1 (elastic#14690)
  ...

.github/workflows/microbenchmark.yml

@@ -8,6 +8,7 @@ on:
     branches:
       - main
       - "8.[0-9]+"
+      - "8.x"
     paths-ignore:
       - '**.md'
       - '**.asciidoc'

.mergify.yml

@@ -174,18 +174,34 @@ pull_request_rules:
           branches, such as:
           * `backport-7.17` is the label to automatically backport to the 7.17 branch.
           * `backport-8./d` is the label to automatically backport to the `8./d` branch. `/d` is the digit.
+          * `backport-8.x` is the label to automatically backport to the `8.x` branch.
 
-          **NOTE**: `backport-skip` has been added to this pull request.
+  - name: add backport-8.x for the all the PRs targeting main if no skipped or assigned already
+    conditions:
+      - -label~=^(backport-skip|backport-8.x)$
+      - base=main
+    actions:
+      comment:
+        message: |
+          `backport-8.x` has been added to help with the transition to the new branch `8.x`.
+          If you don't need it please use `backport-skip` label.
       label:
         add:
-          - backport-skip
+          - backport-8.x
   - name: remove backport-skip label
     conditions:
       - label~=^backport-\d
     actions:
       label:
         remove:
           - backport-skip
+  - name: remove backport-8.x label if backport-skip is present
+    conditions:
+      - label~=^backport-skip
+    actions:
+      label:
+        remove:
+          - backport-8.x
   - name: notify the backport has not been merged yet
     conditions:
       - -merged
@@ -359,10 +375,24 @@ pull_request_rules:
         labels:
           - "backport"
         title: "[{{ destination_branch }}] {{ title }} (backport #{{ number }})"
+  - name: backport patches to 8.x branch
+    conditions:
+      - merged
+      - base=main
+      - label=backport-8.x
+    actions:
+      backport:
+        assignees:
+          - "{{ author }}"
+        branches:
+          - "8.x"
+        labels:
+          - "backport"
+        title: "[{{ destination_branch }}] {{ title }} (backport #{{ number }})"
   - name: backport patches to 8.16 branch
     conditions:
       - merged
-      - base=8.x
+      - base=main
       - label=backport-8.16
     actions:
       backport:
@@ -376,7 +406,7 @@ pull_request_rules:
   - name: backport patches to 8.17 branch
     conditions:
       - merged
-      - base=8.x
+      - base=main
       - label=backport-8.17
     actions:
       backport: