Copy button in Enable Review App modal is broken

Summary

When Enabling a Review App from the environments page, and trying to copy the snippet, the copy button is broken and does not actually copy anything.

Steps to reproduce

Go to Environments > Enable review app. Try to copy the text with the copy button.

Example Project

https://gitlab.com/gdoyle/ux-scorecard-review-apps/-/environments

What is the current bug behavior?

Copy button doesn't copy the text

What is the expected correct behavior?

Copy button should copy the text

Relevant logs and/or screenshots

Screen_Shot_2022-02-10_at_4.12.06_PM

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info 
(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check 
(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)


(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)


(we will only investigate if the tests are passing)

Possible fixes