adb: Set min_sdk_version to "30"

Just a cosmetic cleanup since "R" resolves to 30 as well.

Test: m
Bug: 171330443
Change-Id: I7db2d84953716bd0d4a7f9f3243e82e5ac1724aa
diff --git a/apex/Android.bp b/apex/Android.bp
index ddb17da..ef4a50b 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -1,7 +1,7 @@
 apex_defaults {
     name: "com.android.adbd-defaults",
     updatable: true,
-    min_sdk_version: "R",
+    min_sdk_version: "30",
 
     binaries: ["adbd"],
     compile_multilib: "both",