Don't remove entries for overriddable modules

Previously, when there is apex_set that is overriding another module,
the entry for the overridden module is removed from apexkeys.txt.
However, this is wrong because the existence of the apex_set module
doesn't necessary mean that the module is insatalled instead of the
overridden module. That is determined by PRODUCT_PACKAGES which Soong
has no knowledge of. Therefore, we don't delete the entry for the
overridden (actually possibly overridable) modules in the file.

Bug: 158729168
Test: m
Merged-In: I85d0c756f862323bae556bf657d66ec50038985f
(cherry picked from commit ac5e79f9009400d1020bf45f30c3864bde163b76)
Change-Id: I85d0c756f862323bae556bf657d66ec50038985f
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 7159a45..eef6f42 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -5234,7 +5234,7 @@
 	apexKeysText := ctx.SingletonForTests("apex_keys_text")
 	content := apexKeysText.MaybeDescription("apexkeys.txt").BuildParams.Args["content"]
 	ensureContains(t, content, `name="myapex_set.apex" public_key="PRESIGNED" private_key="PRESIGNED" container_certificate="PRESIGNED" container_private_key="PRESIGNED" partition="system"`)
-	ensureNotContains(t, content, "myapex.apex")
+	ensureContains(t, content, `name="myapex.apex" public_key="PRESIGNED" private_key="PRESIGNED" container_certificate="PRESIGNED" container_private_key="PRESIGNED" partition="system"`)
 }
 
 func TestMain(m *testing.M) {