Build/Test Tools: Avoid npx when running build and test tooling.

[adimoldovan]

Trac ticket: 65864

npx downloads a package and its dependencies from the registry when it cannot find that package locally, then runs the install scripts of everything it downloaded. Each call is a point where a compromised package can run code during a build.

This patch replaces every npx call in the repository with npm exec --no, which runs an installed binary and fails when the package is missing.
update-browserslist-db is now a devDependency at 1.3.1. browserslist already required it as ^1.2.3, so the lockfile hoists a package that was present and adds none.

Testing instructions

1. Run npm ci.
2. Run npm exec --no -- playwright --version. It prints the installed version and downloads nothing.
3. Delete node_modules/update-browserslist-db and run npm exec --no -- update-browserslist-db. It fails with npx canceled due to missing packages and no YES option instead of fetching the package. Restore the tree with npm ci.
4. Run grunt qunit and confirm the QUnit tests still run.
5. Confirm the end-to-end and performance workflows pass on this pull request.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Opus 5
Used for: Auditing the npx call sites. I reviewed and verified the result, including the npm exec --no behavior described above.

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[github-actions]

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[github-actions]

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[Copilot]

Pull request overview

This PR hardens the build/test toolchain by removing npx usage (which can implicitly download and run install scripts) and switching to npm exec --no so tooling runs only when already present in the workspace.

Changes:

• Replace npx invocations with npm exec --no in Grunt tasks and GitHub Actions workflows.
• Add update-browserslist-db@1.3.1 as a devDependency and update the lockfile accordingly.
• Update the QUnit Playwright config comment to reflect the CI browser strategy (system Chrome channel).

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/qunit/playwright.config.js	Updates CI-related comment for Playwright browser selection.
package.json	Adds update-browserslist-db as a pinned devDependency.
package-lock.json	Updates lock entries to reflect the added/pinned dependency version.
Gruntfile.js	Switches QUnit, package update, and Browserslist update tasks from npx to npm exec --no.
.github/workflows/reusable-performance-test-v2.yml	Uses npm exec --no for Playwright browser installation in performance workflow.
.github/workflows/reusable-end-to-end-tests.yml	Uses npm exec --no for Playwright browser installation in E2E workflow.

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