Do not assert if process survives kill.
Summary:
If process survives kill, an error message is already printed to
indicate the problem. Since we cannot hope to kill the process,
gracefully handle this case.
BUG: 365766
Test Plan: Manual testing.
Reviewers: KDevelop, brauch
Reviewed By: KDevelop, brauch
Subscribers: brauch, kdevelop-devel
Differential Revision: https://phabricator.kde.org/D2195