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/java/testing.go b/java/testing.go
index e2ff5cd..8860b45 100644
--- a/java/testing.go
+++ b/java/testing.go
@@ -214,15 +214,15 @@
 	)
 }
 
-// FixtureConfigureUpdatableBootJars configures the updatable boot jars in both the
+// FixtureConfigureApexBootJars configures the apex boot jars in both the
 // dexpreopt.GlobalConfig and Config.productVariables structs. As a side effect that enables
 // dexpreopt.
-func FixtureConfigureUpdatableBootJars(bootJars ...string) android.FixturePreparer {
+func FixtureConfigureApexBootJars(bootJars ...string) android.FixturePreparer {
 	return android.GroupFixturePreparers(
 		android.FixtureModifyProductVariables(func(variables android.FixtureProductVariables) {
-			variables.UpdatableBootJars = android.CreateTestConfiguredJarList(bootJars)
+			variables.ApexBootJars = android.CreateTestConfiguredJarList(bootJars)
 		}),
-		dexpreopt.FixtureSetUpdatableBootJars(bootJars...),
+		dexpreopt.FixtureSetApexBootJars(bootJars...),
 
 		// Add a fake dex2oatd module.
 		dexpreopt.PrepareForTestWithFakeDex2oatd,