[FIXED JENKINS-24316] Fixed unknown task icon src path construction

(cherry picked from commit 286337ea39c0db6e056af61e616736bafc5f0581)
Readd static resource path for task icons [JENKINS-24316]

Missed this in previous commit - bad idea making even small changes late at night ;)

(cherry picked from commit 3daa6a97b02635d672e7646e83edb93abf50db06)