Follow "atomic" to "group" refactoring.

Remove noisy logging about UIDs that are relying on default cache
quota of 64MiB.

Move away from yucky old statfs() and use statvfs() instead.

Test: /data/nativetest/installd_cache_test/installd_cache_test
Bug: 35812899, 35684969, 36482620
Change-Id: I3d68da97eac2ebcda489bdf9d27061cac5b3f7cc
diff --git a/cmds/installd/utils.h b/cmds/installd/utils.h
index abe6830..a4eb1f6 100644
--- a/cmds/installd/utils.h
+++ b/cmds/installd/utils.h
@@ -66,7 +66,7 @@
 
 constexpr const char* kXattrInodeCache = "user.inode_cache";
 constexpr const char* kXattrInodeCodeCache = "user.inode_code_cache";
-constexpr const char* kXattrCacheAtomic = "user.cache_atomic";
+constexpr const char* kXattrCacheGroup = "user.cache_group";
 constexpr const char* kXattrCacheTombstone = "user.cache_tombstone";
 
 int create_pkg_path(char path[PKG_PATH_MAX],