CI: Clean up Node.js installation in GitHub actions (#5322)

- Remove actions installing old Node.js versions no longer used (`14`
  and `16`)
- Rename `latest` action to `active-lts` to clearly signal intent (a
  separate `latest` or `current` action that tests non-lts, can be
  created in a follow up commit)
- Remove `18` action, and replace any usage of it with
  `oldest-maintenance-lts`
- Remove `setup` action and replace any usage of it with `active-lts`
- Move `install` action to after the first Node.js install action that
  actually needs it, instead of first installing one Node.js version,
  only to install another right after
- Change any direct usage of `actions/setup-node` to use our own Node.js
  installation actions instead, when a matrix is not used.

Author: watson

.github/actions/node/14/action.yml

@@ -0,0 +1,9 @@
+name: Node.js Active LTS
+description: Install the current Active LTS version of Node.js
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v4
+      with:
+        cache: yarn
+        node-version: '22'

.github/actions/node/16/action.yml

@@ -0,0 +1,9 @@
+name: Node.js Newst Maintenance LTS
+description: Install the newest Maintenance LTS version of Node.js
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v4
+      with:
+        cache: yarn
+        node-version: '20'

.github/actions/node/18/action.yml

@@ -1,5 +1,5 @@
-name: Node Setup
-description: Install Node.js
+name: Node.js Oldest Maintenance LTS
+description: Install the oldest Maintenance LTS version of Node.js
 runs:
   using: composite
   steps:

.github/actions/node/20/action.yml

@@ -4,14 +4,13 @@ runs:
   using: composite
   steps:
     - uses: ./.github/actions/testagent/start
-    - uses: ./.github/actions/node/setup
+    - uses: ./.github/actions/node/oldest-maintenance-lts
     - uses: ./.github/actions/install
-    - uses: ./.github/actions/node/oldest
     - run: yarn test:plugins:ci
       shell: bash
     - run: yarn test:plugins:upstream
       shell: bash
-    - uses: ./.github/actions/node/latest
+    - uses: ./.github/actions/node/active-lts
     - run: yarn test:plugins:ci
       shell: bash
     - run: yarn test:plugins:upstream