Do not alter the state of the Scheduler while evaluating

Summary:
This differential does a few rewrites, removes a few logs from the console and essentially removes the shutdown decision from the evaluation algorithm.

• Avoided multiple evaluations while loading a schedule, introduced a new Scheduler state for this purpose.
• Prevented moving jobs in the list when option "Sort jobs by Altitude and Priority" is enabled, added tips.
• Reduced amount of logs, fix date display, fix some logs.
• Avoided evaluating a repeating job that just completed, shorted to completion.
• Rewrote, clarified and added fixmes and asserts in the final part of evaluation, sequencing jobs (no change).
• Moved decision to shutdown from the evaluation function off to the status check function.

Test Plan:
Verify this differential brings no change of behavior with the all scheduler test vectors.
Observe the console reduced output as most technical logs were moved to the file journal.
Observe the console as loading a dozen schedule jobs does not result in dozens of evaluations.
Observe move buttons following the state of option "Sort jobs by Altitude and Priority".

Reviewers: mutlaqja, wreissenberger

Reviewed By: mutlaqja

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D15937