Epoch entity endBlock overlaps startBlock of next epoch

Issue

Epoch endBlock should be one block before startBlock of next Epoch to avoid overlapping.

Solution

This can be fixed by calculating endBlock = startBlock + epochLength - 1

Current Behaviour

By querying the endpoint https://gateway.testnet.thegraph.com/network you get these results.

Query

query MyQuery {
  epoches(orderBy:"startBlock", orderDirection: "desc") {
    id
    endBlock
    startBlock
  }
}

Result

{
  "data": {
    "epoches": [
      {
        "endBlock": 8366425,
        "id": "719",
        "startBlock": 8366148
      },
      {
        "endBlock": 8366148,
        "id": "718",
        "startBlock": 8365871
      },
}

The issue names no source file or test. Start by reproducing the epoch query at the listed gateway endpoint, then locate where epoch endBlock is calculated; done when adjacent epochs no longer share a boundary and the query shows each endBlock one block before the next startBlock.