clippy(install): fix collapsible_if lint

[xtqqczze]

https://rust-lang.github.io/rust-clippy/master/#collapsible_if

How it was applied

cargo +stable clippy -p uu_install --fix --all-targets --all-features -- -A clippy::all -W clippy::collapsible_if
cargo +stable fmt --all -- --emit files

Closes #11274

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/seq/seq-epipe is now being skipped but was previously passing.
Congrats! The gnu test tests/cut/cut-huge-range is now passing!

[cakebaker]

Thanks!