**What type of PR is this?**
Other
**What does this PR do? Why is it needed?**
This pull request removes `NUMBER_OF_COLUMNS` and
`MAX_CELLS_IN_EXTENDED_MATRIX` configuration.
**Other notes for review**
Please read commit by commit, with commit messages.
**Acknowledgements**
- [x] I have read
[CONTRIBUTING.md](https://github.com/prysmaticlabs/prysm/blob/develop/CONTRIBUTING.md).
- [x] I have included a uniquely named [changelog fragment
file](https://github.com/prysmaticlabs/prysm/blob/develop/CONTRIBUTING.md#maintaining-changelogmd).
- [x] I have added a description to this PR with sufficient context for
reviewers to understand this PR.
* Fixed metadata extraction on Windows by correctly splitting file paths
* `TestExtractFileMetadata`: Refactor a bit.
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Co-authored-by: Manu NALEPA <enalepa@offchainlabs.com>
