Use frozen lockfile for test dependencies in CI (#4442)

* Use frozen lockfile for test dependencies in CI

This might be causing more Playwright issues.

* Bump Playwright

Mostly just to trigger a reinstall of dependencies since it is cached
and still failing.

Once updated it errors saying install needs to run so add that too.

ci/dev/postinstall.sh

@@ -6,27 +6,28 @@ main() {
 
   echo "Installing code-server test dependencies..."
 
+  local args=(install)
+  if [[ ${CI-} ]]; then
+    args+=(--frozen-lockfile)
+  fi
+
   cd test
-  yarn install
+  yarn "${args[@]}"
   cd ..
 
   cd vendor
   echo "Installing vendor dependencies..."
 
-  # * We install in 'modules' instead of 'node_modules' because VS Code's extensions
-  # use a webpack config which cannot differentiate between its own node_modules
-  # and itself being in a directory with the same name.
-  #
-  # * We ignore scripts because NPM/Yarn's default behavior is to assume that
+  # We install in 'modules' instead of 'node_modules' because VS Code's
+  # extensions use a webpack config which cannot differentiate between its own
+  # node_modules and itself being in a directory with the same name.
+  args+=(--modules-folder modules)
+
+  # We ignore scripts because NPM/Yarn's default behavior is to assume that
   # devDependencies are not needed, and that even git repo based packages are
-  # assumed to be compiled. Because the default behavior for VS Code's `postinstall`
-  # assumes we're also compiled, this needs to be ignored.
-
-  local args=(install --modules-folder modules --ignore-scripts)
-
-  if [[ ${CI-} ]]; then
-    args+=("--frozen-lockfile")
-  fi
+  # assumed to be compiled. Because the default behavior for VS Code's
+  # `postinstall` assumes we're also compiled, this needs to be ignored.
+  args+=(--ignore-scripts)
 
   yarn "${args[@]}"