Inline formatMsg helper into monitoring and canvas plugins

[DianaDerevyankina]

Summary

Inlined code of src/plugins/kibana_legacy/public/notify/lib/format_msg.ts to monitoring and canvas plugins.

Checklist

Delete any items that are not applicable to this PR.

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Unit or functional tests were updated or added to match the most common scenarios

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[kibana-ci]

💚 Build Succeeded

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• Commit: f79459b
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Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
canvas	1061	1062	+1
monitoring	445	446	+1
total			+2

Async chunks

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

id	before	after	diff
canvas	1015.0KB	1015.0KB	-2.0B
monitoring	438.0KB	438.9KB	+930.0B
total			+928.0B

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
canvas	17.4KB	18.1KB	+778.0B
monitoring	23.7KB	23.6KB	-142.0B
total			+636.0B

History

• 💔 Build #6487 failed 3bad2c3

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

cc @dziyanadzeraviankina

[stratoula]

Closing this in favor of #118672
I moved the changes introduced to this PR in a bigger one that actually removes the kibana_legacy plugin.