Utilize `assertFalse` and `assertTrue` methods.

Summary:
Ref D8460.

Use `$this->assertFalse(...)` and `$this->assertTrue(...)` instead of `$this->assertEqual(false, ...)` and `$this->assertEqual(true, ...)` respectively.

Test Plan: `arc unit`

Reviewers: #blessed_reviewers, epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D8461