Rename UpdatableBootJars to ApexBootJars.

Note that ART apex boot jars and core-icu4j are exceptions here as they
are not part of ApexBootJars. ART apex boot jars are defined in their
own variable, while core-icu4j is treated as a regular non-updatable
boot jar.

Bug: 191127295
Test: atest CtsClasspathsTestCases
Change-Id: I3cea3d82ef521655a1a5ffa8cae2258ab9d08bfc
diff --git a/apex/bootclasspath_fragment_test.go b/apex/bootclasspath_fragment_test.go
index 4b1600e..a1d7797 100644
--- a/apex/bootclasspath_fragment_test.go
+++ b/apex/bootclasspath_fragment_test.go
@@ -734,7 +734,7 @@
 		prepareForTestWithMyapex,
 		// Configure bootclasspath jars to ensure that hidden API encoding is performed on them.
 		java.FixtureConfigureBootJars("com.android.art:baz", "com.android.art:quuz"),
-		java.FixtureConfigureUpdatableBootJars("myapex:foo", "myapex:bar"),
+		java.FixtureConfigureApexBootJars("myapex:foo", "myapex:bar"),
 		// Make sure that the frameworks/base/Android.bp file exists as otherwise hidden API encoding
 		// is disabled.
 		android.FixtureAddTextFile("frameworks/base/Android.bp", ""),