Using zcat for gzipped files is unnecessary for concatenation

[jfy133]

Describe the bug
@lindenb pointed out we are currently using zcat to combine FASTQ files in AdapterRemoval. This is unncessary and can just use standard cat

We should remove all unncessary zcat for performance improvements!

[jfy133]

https://github.com/jfy133/eager/tree/zcat_to_cat

But

1. Need to check output looks correct
2. Lots of linting errors due to major nf-core tools update

So will take a bit longer