[9.20] chg: ci: Test development version of libuv in CI

Recently, a broken version of libuv was released breaking BIND on
several platforms. The offending [commit](https://github.com/libuv/libuv/issues/5030) was on the development branch
for months, but we didn't notice.

In nightly pipelines, build the current 'main' (actually 'v1.x') branch
of libuv and run the unit and system tests against it.

Backport of MR !11647

Merge branch 'backport-stepan/prelease-testing-for-libuv-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!11842