* indexer: Pad gas estimates

Indexer tests flake fairly often due to out of gas errors. Case in point below, from a recent test run. This PR updates the indexer tests to pad gas estimates by 20%. This technique is used elsewhere in the indexer E2E tests, but wasn't being applied consistently.

```json
{
  "from": "0x15d34aaf54267db7d7c367839aaf71a00a2c6a65",
  "gas": "0x1f3cc",
  "gasUsed": "0x1edb1",
  "to": "0x978e3286eb805934215a88694d80b09aded68d90",
  "input": "0x",
  "error": "execution reverted",
  "calls": [
    {
      "from": "0x978e3286eb805934215a88694d80b09aded68d90",
      "gas": "0x1889b",
      "gasUsed": "0x1889b",
      "to": "0x8887e7568e81405c4e0d4caaabdda949e3b9d4e4",
      "input": "0x",
      "error": "out of gas",
      "calls": [
        {
          "from": "0x978e3286eb805934215a88694d80b09aded68d90",
          "gas": "0x15560",
          "gasUsed": "0x1f37",
          "to": "0x1c23a6d89f95ef3148bcda8e242cab145bf9c0e4",
          "input": "0xcc731b02",
          "output": "0x0000000000000000000000000000000000000000000000000000000001312d00000000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000003b9aca0000000000000000000000000000000000000000000000000000000000000f424000000000000000000000000000000000ffffffffffffffffffffffffffffffff",
          "calls": [
            {
              "from": "0x1c23a6d89f95ef3148bcda8e242cab145bf9c0e4",
              "gas": "0x13d07",
              "gasUsed": "0xba8",
              "to": "0xffba8944650e26653823658d76a122946f27e2f2",
              "input": "0xcc731b02",
              "output": "0x0000000000000000000000000000000000000000000000000000000001312d00000000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000003b9aca0000000000000000000000000000000000000000000000000000000000000f424000000000000000000000000000000000ffffffffffffffffffffffffffffffff",
              "value": "0x0",
              "type": "DELEGATECALL"
            }
          ],
          "type": "STATICCALL"
        }
      ],
      "value": "0xde0b6b3a7640000",
      "type": "DELEGATECALL"
    }
  ],
  "value": "0xde0b6b3a7640000",
  "type": "CALL"
}
```

* Update indexer/e2e_tests/bridge_transactions_e2e_test.go
Co-authored-by: refcell <abigger87@gmail.com>

---------
Co-authored-by: refcell <abigger87@gmail.com>