[SPARK-3490] Disable SparkUI for tests (backport into 1.1)

Original PR: #2363

Author: Andrew Or <andrewor14@gmail.com>

Closes #2415 from andrewor14/disable-ui-for-tests-1.1 and squashes the following commits:

8d9df5a [Andrew Or] Oops, missed one.
509507d [Andrew Or] Backport #2363 (SPARK-3490) into branch-1.1