This includes the following commits:

original: 9eb222c1
hotfix1: 8c997933
hotfix2: a4f24123
scalastyle check: 609c4923

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Original patch #6441
Branch-1.3 patch #6602

Author: Andrew Or <andrew@databricks.com>

Closes #6598 from andrewor14/demarcate-tests-1.4 and squashes the following commits:

4c3c566 [Andrew Or] Merge branch 'branch-1.4' of github.com:apache/spark into demarcate-tests-1.4
e217b78 [Andrew Or] [SPARK-7558] Guard against direct uses of FunSuite / FunSuiteLike
46d4361 [Andrew Or] Various whitespace changes (minor)
3d9bf04 [Andrew Or] Make all test suites extend SparkFunSuite instead of FunSuite
eaa520e [Andrew Or] Fix tests?
b4d93de [Andrew Or] Fix tests
634a777 [Andrew Or] Fix log message
a932e8d [Andrew Or] Fix manual things that cannot be covered through automation
8bc355d [Andrew Or] Add core tests as dependencies in all modules
75d361f [Andrew Or] Introduce base abstract class for all test suites