BUG/MEDIUM: mworker/cli: fix user and operator permission via @@<pid> in master CLI

BUG/MEDIUM: mworker/cli: fix user and operator permission via @@<pid> in master CLI

When @@<pid> is matched in pcli_parse_request(), no "operator -" or
"user -" is being sent before the command, like it's done for @<pid>.

It leads to privileges not being respected and commands are sent as
admin.

Fix this by applying the access-level downgrade in the @@<pid> path,
like it's done for @<pid>.

Must be backported to 3.2.

Reported-by: Omkhar Arasaratnam <omkhar@linkedin.com>