MINOR: remove never thrown exception

[bmscomp]

This is a too minor pull request that aims to remove a never thrown exception from testUnsignedReadVarlongUnrolled on ByteUtilsBenchmark.java

Committer Checklist (excluded from commit message)

• [x] Verify design and implementation
• [x] Verify test coverage and CI build status
• [x] Verify documentation (including upgrade notes)

[chia7712]

@bmscomp please remove unused import import java.io.IOException;

[bmscomp]

@chia7712 Nice catch, done