util: reduce inspection depth default to five

To minimize potential problems with the higher util.inspect() depth default it is lowered to five as a intermediate step.

I added the don't-land-on labels instead of marking this as semver-major since this relies on a semver-major commit.

Refs: https://github.com/nodejs/node/pull/22846#issuecomment-427894307

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines