feat: add github notification for CI steps (#8485)

(cherry picked from commit cefd95f)

Author: pkoutsovasilis

.buildkite/bk.integration.pipeline.yml

@@ -16,6 +16,9 @@ env:
 steps:
   - label: Start ESS stack for integration tests
     key: integration-ess
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - ESS stack provision"
     env:
       ASDF_TERRAFORM_VERSION: 1.9.2
     command: |
@@ -31,6 +34,9 @@ steps:
 
   - group: "Extended runtime leak tests"
     key: extended-integration-tests
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - Runtime leak tests"
     depends_on:
       - integration-ess
     steps:
@@ -90,6 +96,9 @@ steps:
 
   - group: "Stateful: Windows"
     key: integration-tests-win
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - Windows"
     depends_on:
       - integration-ess
     steps:
@@ -185,6 +194,9 @@ steps:
 
   - group: "Stateful:Ubuntu"
     key: integration-tests-ubuntu
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - Ubuntu"
     depends_on:
       - integration-ess
     steps:
@@ -294,6 +306,9 @@ steps:
 
   - group: "Stateful:Debian"
     key: integration-tests-debian
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - Debian"
     depends_on:
       - integration-ess
     steps:
@@ -351,6 +366,9 @@ steps:
 
   - group: "Stateful(Sudo):RHEL8"
     key: integration-tests-rhel8
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - RHEL8"
     depends_on:
       - integration-ess
     steps:
@@ -373,6 +391,9 @@ steps:
 
   - group: "Kubernetes"
     key: integration-tests-kubernetes
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent-extended-testing - Kubernetes"
     depends_on:
       - integration-ess
       - packaging-containers-x86-64

.buildkite/integration.pipeline.yml

@@ -6,6 +6,9 @@ env:
 steps:
   - group: "Integration tests: packaging"
     key: "int-packaging"
+    notify:
+      - github_commit_status:
+          context: "buildkite/elastic-agent - Packaging"
     steps:
       # Build matrix is not used for packaging in favor to unique step keys
       # Packaging linux/amd64