Modified BT module to be built from source by product

This CL enables the capability to build from source. Haven't implemented the function on any product yet. To enable it, please follow ag/21397639 to define flag on product mk file.

Bug: 268325561
Test: manual test on local
Change-Id: I10f1901ad26ef941465af20d2bb5ab49434baaf3
diff --git a/core/android_soong_config_vars.mk b/core/android_soong_config_vars.mk
index aae17c3..cba0e03 100644
--- a/core/android_soong_config_vars.mk
+++ b/core/android_soong_config_vars.mk
@@ -129,7 +129,7 @@
 # are controlled by the MODULE_BUILD_FROM_SOURCE environment variable by
 # default.
 INDIVIDUALLY_TOGGLEABLE_PREBUILT_MODULES := \
-  bluetooth \
+  btservices \
   permission \
   uwb \
   wifi \