vts_fs_test: Only check /data and /metadata for rw partitions.

Some rw /proc/mounts entries are FUSE.

Also, add some diagnostics for failures.

Bug: 318962836
Test: vts_fs_test on Pixel
Change-Id: I85dec8b37f1a061b1eca597aba3887b598b699f5
diff --git a/fs_mgr/tests/vts_fs_test.cpp b/fs_mgr/tests/vts_fs_test.cpp
index 2f2db0c..9503072 100644
--- a/fs_mgr/tests/vts_fs_test.cpp
+++ b/fs_mgr/tests/vts_fs_test.cpp
@@ -133,9 +133,10 @@
             std::vector<std::string> allowed = {"erofs", "ext4", "f2fs"};
             EXPECT_NE(std::find(allowed.begin(), allowed.end(), entry.fs_type), allowed.end())
                     << entry.mount_point;
-        } else {
+        } else if (std::find(data_fs.begin(), data_fs.end(), entry.mount_point) != data_fs.end()) {
             std::vector<std::string> allowed = {"ext4", "f2fs"};
-            EXPECT_NE(std::find(allowed.begin(), allowed.end(), entry.fs_type), allowed.end());
+            EXPECT_NE(std::find(allowed.begin(), allowed.end(), entry.fs_type), allowed.end())
+                    << entry.mount_point << ", " << entry.fs_type;
         }
     }
 }