fix(test): gc_sync_after_sync (#3160)

gc_sync_after_sync_* tests fail for the following reasons:
1) fork_tail is not properly maintained. A node resets fork tail after state sync but we allowed it to go back on epoch change.
2) in #3099 I didn't account for the fact that we can have chunk in storage whose height is higher than the current head.

Fixes #3133.

Test plan
----------
Run each of the gc_sync_after_sync_* tests 30 tests and observe that there is 0 failure.

chain/chain/src/chain.rs

@@ -529,17 +529,16 @@ impl Chain {
         }
         let prev_epoch_id = self.get_block_header(&head.prev_block_hash)?.epoch_id();
         let epoch_change = prev_epoch_id != &head.epoch_id;
-        let fork_tail = if epoch_change {
+        let mut fork_tail = self.store.fork_tail()?;
+        if epoch_change && fork_tail < gc_stop_height {
             // if head doesn't change on the epoch boundary, we may update fork tail several times
             // but that is fine since it doesn't affect correctness and also we limit the number of
             // heights that fork cleaning goes through so it doesn't slow down client either.
             let mut chain_store_update = self.store.store_update();
             chain_store_update.update_fork_tail(gc_stop_height);
             chain_store_update.commit()?;
-            gc_stop_height
-        } else {
-            self.store.fork_tail()?
-        };
+            fork_tail = gc_stop_height;
+        }
         let mut gc_blocks_remaining = gc_blocks_limit;
 
         // Forks Cleaning
@@ -925,7 +924,8 @@ impl Chain {
         // Get header we were syncing into.
         let header = self.get_block_header(&sync_hash)?;
         let prev_hash = *header.prev_hash();
-        let gc_height = std::cmp::min(head.height + 1, header.height());
+        let sync_height = header.height();
+        let gc_height = std::cmp::min(head.height + 1, sync_height);
 
         // GC all the data from current tail up to `gc_height`
         let tail = self.store.tail()?;
@@ -946,7 +946,9 @@ impl Chain {
 
         // Clear Chunks data
         let mut chain_store_update = self.mut_store().store_update();
-        chain_store_update.clear_chunk_data(gc_height)?;
+        // The largest height of chunk we have in storage is head.height + 1
+        let chunk_height = std::cmp::min(head.height + 2, sync_height);
+        chain_store_update.clear_chunk_data(chunk_height)?;
         chain_store_update.commit()?;
 
         // clear all trie data
@@ -996,6 +998,7 @@ impl Chain {
         // New Tail can not be earlier than `prev_block.header.inner_lite.height`
         chain_store_update.update_tail(new_tail);
         // New Chunk Tail can not be earlier than minimum of height_created in Block `prev_block`
+        println!("resetting chunk tail to {}", new_chunk_tail);
         chain_store_update.update_chunk_tail(new_chunk_tail);
         chain_store_update.commit()?;