Remove references to deleted .ci folder

The folder was deleted in PR #173745

.bazelignore

@@ -3,7 +3,6 @@
 # https://github.com/bazelbuild/bazel/issues/7093
 # https://github.com/bazelbuild/bazel/issues/8106
 .buildkite
-.ci
 .chromium
 .git
 .github

.eslintignore

@@ -15,7 +15,6 @@ node_modules
 target
 snapshots.js
 
-!/.ci
 !/.eslintrc.js
 !.storybook
 !.buildkite

.github/CODEOWNERS

@@ -1148,7 +1148,6 @@ x-pack/plugins/infra/server/lib/alerting @elastic/obs-ux-management-team
 /src/setup_node_env/ @elastic/kibana-operations
 /src/cli/keystore/ @elastic/kibana-operations
 /src/cli/serve/ @elastic/kibana-operations
-/.ci/es-snapshots/ @elastic/kibana-operations
 /.github/workflows/ @elastic/kibana-operations
 /vars/ @elastic/kibana-operations
 /.bazelignore @elastic/kibana-operations

.gitignore

@@ -81,9 +81,6 @@ package-lock.json
 npm-debug.log*
 .tern-project
 .nyc_output
-.ci/pipeline-library/build/
-.ci/runbld
-.ci/bash_standard_lib.sh
 .gradle
 .vagrant
 .envrc

docs/developer/advanced/upgrading-nodejs.asciidoc

@@ -13,10 +13,6 @@ Before making a PR to upgrade Node.js, we must first <<start-new-nodejs-build,ge
 The required version of Node.js is listed in several different files throughout the {kib} source code.
 These files must be updated when upgrading Node.js:
 
-  - {kib-repo}blob/{branch}/.ci/Dockerfile[`.ci/Dockerfile`] - The version is specified in the `NODE_VERSION` constant.
-    This is used to pull the relevant image from https://hub.docker.com/_/node[Docker Hub].
-    Note that Docker Hub can take 24+ hours to be updated with the new images after a new release of Node.js, so if you're upgrading Node.js in Kibana just after the official Node.js release, you have to check if the new images are present on Docker Hub.
-    If they are not, and the update is urgent, you can skip this file and update it later once Docker Hub has been updated.
   - {kib-repo}blob/{branch}/.node-version[`.node-version`]
   - {kib-repo}blob/{branch}/.nvmrc[`.nvmrc`]
   - {kib-repo}blob/{branch}/package.json[`package.json`] - The version is specified in the `engines.node` field (if possible, also upgrade `@types/node` to match the new version, both under `devDependencies` and `resolutions`).

src/dev/precommit_hook/casing_check_config.js

@@ -40,7 +40,6 @@ export const IGNORE_FILE_GLOBS = [
   'packages/kbn-utility-types/test-d/**/*',
   'Dockerfile*',
   'vars/*',
-  '.ci/pipeline-library/**/*',
   'packages/kbn-test/jest-preset.js',
   'packages/kbn-test/*/jest-preset.js',
   'test/package/Vagrantfile',