pw_kvs: Count deleted entries in redundancy update

When redundancy is updated, include the deleted entries in the count of
valid entries that may have needed duplicate entries.

This prevents false positives of found corruption when upgrading a KVS's
redundancy level.

Change-Id: I6d04b501057688be8b9aa2dc41e0dd49bc72336f
diff --git a/pw_kvs/key_value_store.cc b/pw_kvs/key_value_store.cc
index 6e56dc1..170ddf0 100644
--- a/pw_kvs/key_value_store.cc
+++ b/pw_kvs/key_value_store.cc
@@ -269,7 +269,7 @@
     bool other_errors = error_detected_;
     error_detected_ = true;
 
-    if (!other_errors && entry_copies_missing == size()) {
+    if (!other_errors && entry_copies_missing == entry_cache_.total_entries()) {
       INF("KVS configuration changed to redundancy of %zu total copies per key",
           redundancy());
       return Status::OUT_OF_RANGE;