Deployment tooltips are hard to focus/hover on

Summary

The users need to see data about deployments by hovering on the respective deployments in the chart.

It is very hard to make a deployment tooltip active. We should make this easier.

Screen_Recording_2020-08-18_at_12.31.10

Steps to reproduce

  1. Access this dashboard: https://gitlab.com/gitlab-org/monitor/monitor-sandbox/-/metrics/all_chart_types.yml?start=2020-08-06T09%3A28%3A42Z&end=2020-08-18T09%3A28%3A42Z
  2. Select a custom range that spans from 2020-08-06 12:00:00 to 2020-08-18 12:00:00
  3. Try to hover over the deployment icons in order to activate the deployment tooltips

What is the current bug behavior?

Activating the deployment tooltip by hovering over the deployment icon is very hard to do, sometimes impossible.

What is the expected correct behavior?

Hovering over the icon should always display the deployment tooltip.

Video

Screen_Recording_2020-08-18_at_12.31.10

Output of checks

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Results of GitLab environment info

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`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

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(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

(If you can, link to the line of code that might be responsible for the problem)