refactor(test): update tests for Kotlin conversion of AutocryptHeaderParser and AutocryptGossipHeaderParser

Author: shamim-emon

legacy/core/src/test/java/com/fsck/k9/autocrypt/AutocryptGossipHeaderParserTest.kt

@@ -18,7 +18,7 @@ import org.junit.Test
 
 class AutocryptGossipHeaderParserTest {
 
-    private val autocryptGossipHeaderParser = AutocryptGossipHeaderParser.getInstance()
+    private val autocryptGossipHeaderParser = AutocryptGossipHeaderParser.Companion.instance
 
     @Before
     fun setUp() {

legacy/core/src/test/java/com/fsck/k9/autocrypt/AutocryptHeaderParserTest.java

@@ -20,7 +20,7 @@
 
 
 public class AutocryptHeaderParserTest extends RobolectricTest {
-    AutocryptHeaderParser autocryptHeaderParser = AutocryptHeaderParser.getInstance();
+    AutocryptHeaderParser autocryptHeaderParser = AutocryptHeaderParser.Companion.getInstance();
 
     @Before
     public void setUp() throws Exception {