Tweaked the get_domains_by_type() to return alphabetically

[cameronterry]

This method was causing an "error" in the unit tests as the array mismatched the return.

Not really an "bug" per se, but the ordering of results from get_domains_by_type() was weird and making it return alphabetically - A to Z - makes more sense.

Resolves the following unit test error:

4) MediaDomainsTest::test_get_media_domains_manual
Media domains set by constant.
Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
 Array (
     0 => DM_Domain Object (
-        'id' => 18
+        'id' => 20
         'blog_id' => 17
         'is_primary' => false
-        'domain' => 'cdn1.mappeddomain1.test'
+        'domain' => 'cdn3.mappeddomain1.test'
         'active' => true
         'is_https' => true
         'type' => 2
@@ @@
     )
     1 => DM_Domain Object (...)
     2 => DM_Domain Object (
-        'id' => 20
+        'id' => 18
         'blog_id' => 17
         'is_primary' => false
-        'domain' => 'cdn3.mappeddomain1.test'
+        'domain' => 'cdn1.mappeddomain1.test'
         'active' => true
         'is_https' => true
         'type' => 2
     )
 )

/home/runner/work/dark-matter/dark-matter/tests/phpunit/domain-mapping/MediaDomainsTest.php:94