MDL-55837 themes: base and canvas themes removed

Look for them in the plugins DB if you still need them.

lib/tests/user_test.php

@@ -360,7 +360,7 @@ class core_user_testcase extends advanced_testcase {
 
         // Test against theme property choices.
         $choices = core_user::get_property_choices('theme');
-        $this->assertArrayHasKey('base', $choices);
+        $this->assertArrayHasKey('bootstrapbase', $choices);
         $this->assertArrayHasKey('clean', $choices);
         $this->assertArrayNotHasKey('unknowntheme', $choices);
         $this->assertArrayNotHasKey('wrongtheme', $choices);