doc: Fix inaccuracy in https.request docs

Checklist

• make -j8 test (UNIX), or vcbuild test nosign (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

doc (https)

Description of change

Remove misleading statement about require('https').globalAgent silently ignoring options passed to require('https').request. Refer to discussion in #9324 (closed).