adds [Performance Testing] Nightly Build Job (#114042)

Adds auto and manual performance tests

If "ITERATION_COUNT_ENV" exist in build job:
- Auto Mode: Checks "ITERATION_COUNT_ENV",
- Manual Mode: Waits for user input,
use provided value to run "n" number of performance tests on parallel
- Sends slack notifications when pipeline finished

.buildkite/pipelines/performance/nightly.yml

@@ -0,0 +1,35 @@
+steps:
+  - block: ":gear: Performance Tests Configuration"
+    prompt: "Fill out the details for performance test"
+    fields:
+      - text: ":arrows_counterclockwise: Iterations"
+        key: "performance-test-iteration-count"
+        hint: "How many times you want to run tests? "
+        required: true
+    if: build.env('ITERATION_COUNT_ENV') == null
+
+  - label: ":male-mechanic::skin-tone-2: Pre-Build"
+    command: .buildkite/scripts/lifecycle/pre_build.sh
+
+  - wait
+
+  - label: ":factory_worker: Build Kibana Distribution and Plugins"
+    command: .buildkite/scripts/steps/build_kibana.sh
+    agents:
+      queue: c2-16
+    key: build
+
+  - label: ":muscle: Performance Tests"
+    command: .buildkite/scripts/steps/functional/performance.sh
+    agents:
+      queue: ci-group-6
+    depends_on: build
+    concurrency: 50
+    concurrency_group: 'performance-test-group'
+
+  - wait: ~
+    continue_on_failure: true
+
+  - label: ":male_superhero::skin-tone-2: Post-Build"
+    command: .buildkite/scripts/lifecycle/post_build.sh
+

.buildkite/scripts/steps/functional/performance.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+set -uo pipefail
+
+if [ -z "${ITERATION_COUNT_ENV+x}" ]; then
+  ITERATION_COUNT="$(buildkite-agent meta-data get performance-test-iteration-count)"
+else
+  ITERATION_COUNT=$ITERATION_COUNT_ENV
+fi
+
+tput setab 2; tput setaf 0; echo "Performance test will be run at ${BUILDKITE_BRANCH} ${ITERATION_COUNT} times"
+
+cat << EOF | buildkite-agent pipeline upload
+steps:
+  - command: .buildkite/scripts/steps/functional/performance_sub.sh
+    parallelism: "$ITERATION_COUNT"
+EOF
+
+
+

.buildkite/scripts/steps/functional/performance_sub.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+source .buildkite/scripts/common/util.sh
+
+.buildkite/scripts/bootstrap.sh
+.buildkite/scripts/download_build_artifacts.sh
+
+cd "$XPACK_DIR"
+
+echo --- Run Performance Tests
+checks-reporter-with-killswitch "Run Performance Tests" \
+  node scripts/functional_tests \
+    --debug --bail \
+    --kibana-install-dir "$KIBANA_BUILD_LOCATION" \
+    --config test/performance/config.ts;