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/android/config.go b/android/config.go
index 396b1a6..00d3e75 100644
--- a/android/config.go
+++ b/android/config.go
@@ -1847,16 +1847,16 @@
 func (c *config) BootJars() []string {
 	return c.Once(earlyBootJarsKey, func() interface{} {
 		list := c.productVariables.BootJars.CopyOfJars()
-		return append(list, c.productVariables.UpdatableBootJars.CopyOfJars()...)
+		return append(list, c.productVariables.ApexBootJars.CopyOfJars()...)
 	}).([]string)
 }
 
-func (c *config) NonUpdatableBootJars() ConfiguredJarList {
+func (c *config) NonApexBootJars() ConfiguredJarList {
 	return c.productVariables.BootJars
 }
 
-func (c *config) UpdatableBootJars() ConfiguredJarList {
-	return c.productVariables.UpdatableBootJars
+func (c *config) ApexBootJars() ConfiguredJarList {
+	return c.productVariables.ApexBootJars
 }
 
 func (c *config) RBEWrapper() string {