[Bug] Memory leak when using block handler without filter

Bug report

For the following subgraph we needed a way to initialize some values (at block 0):
https://github.com/Taraxa-project/taraxa-platform/tree/feature/add-subgraph-for-dpos/packages/dpos-subgraph

When we added a blockHandlers without a filter, it calls the handler for all blocks but the memory increases exponentially until the process is killed due to OOM.

The contents of the handler function doesn't matter. Also tested with an empty function.

Happens in Docker with v0.27.0, v0.28.0, v0.29.0, v0.30

https://user-images.githubusercontent.com/3051409/229186801-46673195-05fa-4f60-baa8-e2c636ee51e0.mp4

Relevant log output

No response

IPFS hash

No response

Subgraph name or link to explorer

No response

Some information to help us out

• Tick this box if this bug is caused by a regression found in the latest release.
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OS information

Linux

Reproduce the report with the linked dpos-subgraph, a block handler without a filter, and graph-node v0.27.0 through v0.30 in Docker on Linux. Trace the block-handler execution path and verify that an empty handler no longer causes memory to grow until the process is killed.