Do not buildQueryFromSavedQuery() on non-existing workboards
Summary:
This is a waste of CPU cycles.
Closes T16247
Test Plan:
* Insert `phlog('WE DO NOT WANT TO BE HERE');` at the beginning of `PhabricatorApplicationSearchEngine::buildQueryFromSavedQuery()`
* Go to the workboard view of a project which has no workboard set up yet
* See that phlog output is emitted before this patch when loading a non-existing workboard, and not emitted after this patch
* Load existing and non-existing workboards of projects, subprojects, and milestones, and see no differences in behavior
Reviewers: O1 Blessed Committers, mainframe98
Reviewed By: O1 Blessed Committers, mainframe98
Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T16247
Differential Revision: https://we.phorge.it/D26461