Move experiment tracking behavior to configuration

What does this MR do?

This is mostly a quality of life fix. I noticed recently that if you run:

Gitlab::Experiment.new(:example).track(:foo) # => log output
experiment(:example).track(:foo) # => calls to Gitlab::Tracking

This is because the raw base class utilizes the configuration, and ApplicationExperiment (the base class utilized when calling experiment) overrides the track method. I figured now that we've normalized this a bit, we should move it up to minimize one aspect of potential developer confusion.

Note:

The same is currently true with our #publish method, but we're working to get that minimized and cleaned up as well, so I'm saving that for a separate MR.

Does this MR meet the acceptance criteria?

Conformity

• I have included changelog trailers, or none are needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.