Increase the max number of records read by kef2ph5

[nick-falco]

kef2ph5 would fail if a file contained more than 10,000 records.

What does this PR do?

Increase the number of records that keftoph5 reads.

Checklist

• This PR is not directly related to an existing issue (which has no PR yet).
• All tests pass.
• Any new or changed features have are documented.
• Changes have been added to CHANGELOG.txt .
• First time contributors have added your name to CONTRIBUTORS.txt .

[dsentinel]

What's the failure mode? Have you hit this?
It's in a while True loop, so It shouldn't be limited, but only works on 10,000 at a time

[nick-falco]

I can send you an example kef file that breaks this if you'd like? I was running into problems when trying to read very large kef files. Increasing the number of records read in each iteration of the loop fixed the issue, likely because it read them all on the first iteration. Please view this as a WIP. I think I need to take another look at this.