Copy additional javascripts with copy-webpack-plugin

Why is this change being made?

This MR uses the copy-webpack-plugin to directly copy 4 additional javascripts over to javascripts/applications and update links to them.

countdown.js used on

• /community/hackathon/index.html
• /company/culture/contribute/index.html

guide-to-the-cloud.js used on

• /resources/guide-to-the-cloud/index.html

image-lazy-load.js used on

• /remote-work-report/index.html

run-experiment.js used on

• /handbook/marketing/inbound-marketing/digital-experience/test/index.html
• /marketing/source/just-commit/reduce-cycle-time/index.html

Webpack was just stripping the entire contents of these javascripts files, rendering them empty.

This is a temporary fix util we can figure out how to properly process these with webpack.

• Related https://gitlab.com/gitlab-com/marketing/inbound-marketing/brand-and-digital/brand-and-digital/-/issues/388
• Related https://gitlab.com/gitlab-com/marketing/inbound-marketing/brand-and-digital/brand-and-digital/-/issues/387

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the "Maintained by" section in on the page being edited.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies.
  • If the changes relate to any part of the project other than updates to content and/or data files please make sure to ping @gl-static-site-editor in a comment for a review and merge. For example changes to .gitlab-ci.yml, JavaScript/CSS/Ruby code or the layout files. (this requirement has been removed pending identification of a new DRI for the handbook)