Bluetooth: Demote ObsoleteSdkInt to a warning

ObsoleteSdkInt is failing when Bluetooth is built with
UNBUNDLED_BUILD_TARGET_SDK_WITH_API_FINGERPRINT=true.

To unblock the build, the error is demoted to a warning
with a TODO to add it back.

Bug: 318814235
Bug: 318719701
Change-Id: I2026a55fcc0b0d919107b620716e45d2154e4c77
Flag: Exempt, Build Change
Test: UNBUNDLED_BUILD_TARGET_SDK_WITH_API_FINGERPRINT=true m lint-check

android/app/Android.bp

@@ -286,11 +286,11 @@ android_app {
     javacflags: ["-Aroom.schemaLocation=packages/modules/Bluetooth/android/app/tests/unit/src/com/android/bluetooth/btservice/storage/schemas"],
 
     lint: {
+        // TODO(b/318814235): Add back ObsoleteSdkInt to this list.
         error_checks: [
             "ExtraText",
             "MissingClass",
             "NewApi",
-            "ObsoleteSdkInt",
             "Recycle",
             "RtlHardcoded",
             "UseSparseArrays",