Do not umount /mnt/vm

It is manually mounted in the init.rc.

Bug: 331320802
Test: boot and check /mnt/vm
Change-Id: I4ac4b0cec7bb1203446700e1cb2b1e142647d672
diff --git a/VolumeManager.cpp b/VolumeManager.cpp
index 7c2b2f2..a7c87a3 100644
--- a/VolumeManager.cpp
+++ b/VolumeManager.cpp
@@ -1036,7 +1036,8 @@
              !StartsWith(test, "/mnt/scratch") &&
 #endif
              !StartsWith(test, "/mnt/vendor") && !StartsWith(test, "/mnt/product") &&
-             !StartsWith(test, "/mnt/installer") && !StartsWith(test, "/mnt/androidwritable")) ||
+             !StartsWith(test, "/mnt/installer") && !StartsWith(test, "/mnt/androidwritable") &&
+             !StartsWith(test, "/mnt/vm")) ||
             StartsWith(test, "/storage/")) {
             toUnmount.push_front(test);
         }