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/sysprop/api/SurfaceFlingerProperties-current.txt b/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt
index 41987fc..ba88acc 100644
--- a/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt
+++ b/services/surfaceflinger/sysprop/api/SurfaceFlingerProperties-current.txt
@@ -1,6 +1,10 @@
 props {
   module: "android.sysprop.SurfaceFlingerProperties"
   prop {
+    api_name: "clear_slots_with_set_layer_buffer"
+    prop_name: "ro.surface_flinger.clear_slots_with_set_layer_buffer"
+  }
+  prop {
     api_name: "color_space_agnostic_dataspace"
     type: Long
     prop_name: "ro.surface_flinger.color_space_agnostic_dataspace"