[SLO] Unregistering from/to fields for histogram indicator

[simianhacker]

Summary

This PR fixes #161861 by adding shouldUnregister to the Controller components for indicator.params.from and indicator.params.to to ensure the fields are unregistered when they are unmounted.

Testing

1. Create a new SLO using the histogram indicator.
2. Set both the "good" and "total" events to use value count
3. Ensure the preview chart displays data
4. Set the "good" events to a range, the previous chart should update.

[apmmachine]

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[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)

[kdelemme]

super fast approval because I tested the fix this AM on my side 😇

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 1a4ecf0

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
observability	1.1MB	1.1MB	+40.0B

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	14	16	+2
securitySolution	411	415	+4
total			+6

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	15	17	+2
securitySolution	490	494	+4
total			+6

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