fix: resolve the errors in GetLightClientUpdatesByRange function

[rupam-04]

What type of PR is this?

Bug fix

What does this PR do? Why is it needed?

1. Remove this line
2. Return HandleError in places where continue is used inside if err != nil
3. Make this requirement 1 vote and not 66%

Which issues(s) does this PR fix?

Fixes #14170

Other notes for review

I am yet to add unit tests for the 3rd change

[CLAassistant]

All committers have signed the CLA.

[rkapka]

Let's not merge without tests to make sure we don't forget about them

[rupam-04]

Let's not merge without tests to make sure we don't forget about them

tests added! Pls let me know if any more changes are required

[Inspector-Butters]

I'm not sure if we even should filter out the blocks with zero SyncComitteeBits. since the light clients themselves check that.
But according to the specs, this will not count as a valid update anyway, so maybe we could save them the trouble of computation and just don't send them invalid updates.
Unless there is another use for this function.

[rkapka]

The full node spec does not require to send only updates with 1 or more participants, but since it's the sync committee that provides an update, having 0 participants essentially means that the sync committee did not give an update.