[Plot] Switching Non-time field values does not enable Apply button.

- Fix Plot configuration for the 'Non-Time' field switching values does not enable the Apply button.

Wrote or re-wrote unit tests (Y/N): N
Ran entire suite of unit tests successfully (Y/N): Y
Verified bug fix with the described replication steps or verified the implementation meets the requirement cited (Y/N): Y
Code coverage requirements satisfied (new code=80%, changed code=at least as high as existing) (Y/N): N
Code review date and attendees: Code review by pull request
Describe potential impact on other areas of the code: Plotting
Describe any test prerequisites for this fix (e.g., restart the database): n/a
For bugs marked "Regression - Yes", describe the cause of the regression: n/a
Did you modify any pom.xml file? If yes, did you thoroughly document your changes and reasons? No