Port QRegExp to QRegularExpression

Summary:
One instance of QString::remove(QRegExp... was replaced to use the
replace overload that takes a QLatin1String.

In RunnerContext::restore, change the regex so that "id" is at least one
character, otherwise using d->launchCounts[id] doesn't make sense.

Reviewers: Plasma, davidedmundson, apol

Reviewed By: apol

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D26194