balooctl monitor: Resume to wait for service

Summary: Keep monitoring until terminated by ctrl+c

Test Plan:
While monitor is running various permutations of

• balooctl stop
• balooctl start
• balooctl restart
• echo otto >> ~/Documents/otto.csv

Reviewers: Baloo, Frameworks, dfaure, alexeymin, mwolff

Reviewed By: mwolff

Subscribers: mwolff

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D10712