Read installed @playwright/test version when building the e2e image tag (TryGhost#27880)

no ref

\`e2e/scripts/load-playwright-container-env.sh\` constructs the
Playwright Docker image tag from the version declared in
\`e2e/package.json\`. Switched from reading the manifest field
(\`devDependencies["@playwright/test"]\`) to reading the installed
package's actual version
(\`require("@playwright/test/package.json").version\`).

Author: 9larsons

e2e/scripts/load-playwright-container-env.sh

@@ -10,7 +10,7 @@ REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
 
 cd "$REPO_ROOT"
 
-PLAYWRIGHT_VERSION="$(node -p 'require("./e2e/package.json").devDependencies["@playwright/test"]')"
+PLAYWRIGHT_VERSION="$(cd e2e && node -p "require('@playwright/test/package.json').version")"
 PLAYWRIGHT_IMAGE="mcr.microsoft.com/playwright:v${PLAYWRIGHT_VERSION}-noble"
 WORKSPACE_PATH="${GITHUB_WORKSPACE:-$REPO_ROOT}"