Sync committee participation sometimes fell down 50% for few slots in the epoch

### Describe the bug

Observed randomly among different runs of simulation tests that sync committee participation fell down the 50% for few slots in the epoch. Which end up having less than 90% average for the epoch with the epoch length of 8 slots for minimal preset.

Slots which are not listed in table below have participation values `1`.

|Slot|node-1-beacon-lodestar|node-2-beacon-lighthouse|
|----|----------------------|------------------------|
|1 | - |- |
|2 | - |- |
|3 | - |- |
|13 | - |- |
|14 | - |- |
|15 | - |- |
|16 | 0 |0 |
|17 | 0.40625 |0.40625 |
|18 | 1 |1 |
|19 | 1 |1 |
|20 | 1 |1 |
|39 | 1 |1 |
|40 | 1 |1 |
|41 | 0.40625 |0.40625 |
|42 | 1 |1 |
|43 | 0.40625 |0.40625 |
|44 | 1 |1 |
|45 | 1 |1 |
|46 | 1 |1 |
|47 | 1 |1 |

### Expected behavior

There should be 100% participation for all slots except the first slot of the altair fork.

### Steps to reproduce

Run sim tests in multiple times.

### Additional context

Check the multi-client logs for the following sim-run attached.

[debug-test-logs-cli (11).zip](https://github.com/ChainSafe/lodestar/files/14301129/debug-test-logs-cli.11.zip)

### Operating system

Linux

### Lodestar version or commit hash

unstable