[Synthetics] Fix monitor summary page layout

[shahzad31]

Summary

After:

Before

[elasticmachine]

Pinging @elastic/uptime (Team:uptime)

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 26c2b9a

Failed CI Steps

• Synthetics @elastic/synthetics Tests

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
synthetics	984.7KB	984.7KB	+16.0B

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[awahab07]

LGTM

[lucasfcosta]

Just post-FF tested this and the layout LGTM for browser monitors, here's what I did:

1. Create a new deployment on Cloud using the 8.5.0-SNAPSHOT tag on CFT
2. Enabled the new Synthetics UI
3. Created a monitor
4. Accessed its details page

I also created an HTTP monitor just in case and checked its layout too, but there was one problem: some of the components never finished loading. Those were the components with details about the run history.

I created a separate issue for that here: #142113 (@paulb-elastic I also moved that to the "primary" column because it seemed significant enough, but lmk if we actually intend to fix that only in 8.6).

[paulb-elastic]

@lucasfcosta thanks for raising. I've put #142113 in the 8.5 column for now, although we'll need to get other 8.5 things finished up first, as the UI won't be for users to use in 8.5, so can go into 8.6 if necessary.