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: I5f5feb7344941d0154f384e3c06279d49b490768
diff --git a/core/soong_config.mk b/core/soong_config.mk
index fb0b80d..d3f983c 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -142,7 +142,7 @@
 $(call add_json_list, ModulesLoadedByPrivilegedModules,  $(PRODUCT_LOADED_BY_PRIVILEGED_MODULES))
 
 $(call add_json_list, BootJars,                          $(PRODUCT_BOOT_JARS))
-$(call add_json_list, UpdatableBootJars,                 $(PRODUCT_APEX_BOOT_JARS))
+$(call add_json_list, ApexBootJars,                      $(PRODUCT_APEX_BOOT_JARS))
 
 $(call add_json_bool, VndkUseCoreVariant,                $(TARGET_VNDK_USE_CORE_VARIANT))
 $(call add_json_bool, VndkSnapshotBuildArtifacts,        $(VNDK_SNAPSHOT_BUILD_ARTIFACTS))