Rename ServiceParams to Integrations::Params

What does this MR do?

This refactor changes the name of ServiceParams (a concern included in some of our controllers) to Integrations::Params. It also allows the service parameter to be named :integration.

This is in service of renaming the Service model to Integration.

As a pure backend-refactoring, this should not change any behavior, or be observable to clients.

Further migration from service to integration is being tracked in #201855 (closed), #201848 (closed).

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have not included a changelog entry because this is an internal change.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

This is an internal developer-facing change. No behavior should be affected by this. Existing tests should all continue to pass.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Related to #210023 (closed)