Rename remaining classes that operate on integrations to use the word "integration" instead of "service"

See #330670 (comment 575341780) for a list of classes to rename (although there may be more). Note that ServiceHook has its own separate issue #335882 (closed).

As part of &2504 (closed) we have started the process of renaming integration classes (#201848 (closed) and #201855 (closed)).

This issue is to:

1. Rename all other classes that operate on integrations to use the word integration instead of service in its name.
2. Where possible these classes should be namespaced in Integrations:: also.
3. Update the regexes needed to support these files in tooling/danger/project_helper.rb !74330 (merged)