Force HALs to explicitly enable legacy method for clearing buffer caches

Some HAL implementations can't support setLayerBuffer multiple times to
clear the per-layer buffer caches. Therefore, default this behavior to
disabled, and allow HALs to explcitily enable this behavior to obtain
the necessary memory savings.

Test: play videos with both true and false on both HIDL and AIDL
Bug: 285561686
Change-Id: I928cef25e35cfc5337db4ceb8581bf5926b4fbe3
diff --git a/services/surfaceflinger/SurfaceFlingerProperties.cpp b/services/surfaceflinger/SurfaceFlingerProperties.cpp
index 20fa091..96c8b54 100644
--- a/services/surfaceflinger/SurfaceFlingerProperties.cpp
+++ b/services/surfaceflinger/SurfaceFlingerProperties.cpp
@@ -375,5 +375,9 @@
     return SurfaceFlingerProperties::ignore_hdr_camera_layers().value_or(defaultValue);
 }
 
+bool clear_slots_with_set_layer_buffer(bool defaultValue) {
+    return SurfaceFlingerProperties::clear_slots_with_set_layer_buffer().value_or(defaultValue);
+}
+
 } // namespace sysprop
 } // namespace android