[7.x] [APM] Removes react-sticky dependency in favor of using CSS (#84589)

[tylersmalley]

Backports the following commits to 7.x:

• [APM] Removes react-sticky dependency in favor of using CSS ([APM] Removes react-sticky dependency in favor of using CSS #84589)

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: b281e38

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
apm	1155	1152	-3

Async chunks

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

id	before	after	diff
apm	3.1MB	3.1MB	-11.3KB
enterpriseSearch	724.8KB	724.7KB	-55.0B
total			-11.4KB

Page load bundle

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

id	before	after	diff
upgradeAssistant	60.2KB	60.1KB	-55.0B

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