Use LTS nodejs in github workflows (#12726)

Currently our GH workflows all use nodejs 18, but that's not compatible with the
stated support range of matrix-js-sdk, which requires the latest LTS nodejs;
so, when we attermpt to `yarn install` on an older nodejs, we get an error.

Switch to LTS nodejs for all the places we set up nodejs.

.github/workflows/end-to-end-tests.yaml

@@ -56,6 +56,7 @@ jobs:
             - uses: actions/setup-node@v4
               with:
                   cache: "yarn"
+                  node-version: "lts/*"
 
             - name: Fetch layered build
               id: layered_build
@@ -121,6 +122,7 @@ jobs:
               with:
                   cache: "yarn"
                   cache-dependency-path: matrix-react-sdk/yarn.lock
+                  node-version: "lts/*"
 
             - name: Install dependencies
               working-directory: matrix-react-sdk
@@ -172,6 +174,7 @@ jobs:
               if: inputs.skip != true
               with:
                   cache: "yarn"
+                  node-version: "lts/*"
 
             - name: Install dependencies
               if: inputs.skip != true