Mark the phony shell_and_utilities_vendor as vendor: true

As part of the make to soong conversion, we are currently autogenerating
android_filesystem soong modules for each partition (system, system_ext,
vendor, ...), with the goal to eventually substitute the kati built
partitions. In order to generate the deps of these partitions, we are
currently using a heuristic to classify the modules in
`PRODUCT_PACKAGES` with the associated partition.

Mark the phony module `shell_and_utilities_vendor` as
`vendor: true` to help with this conversion heursitic.

Bug: 374371755
Test: verified that /bin/awk is present in the autogenerated soong-built
vendor partition

Change-Id: I0a99275fb03fbb9adeb1502734759f433585ef25
diff --git a/shell_and_utilities/Android.bp b/shell_and_utilities/Android.bp
index d5893de..1f5c179 100644
--- a/shell_and_utilities/Android.bp
+++ b/shell_and_utilities/Android.bp
@@ -58,6 +58,7 @@
         "toolbox_vendor",
         "toybox_vendor",
     ],
+    vendor: true,
 }
 
 // shell and utilities for first stage console. The list of binaries are