[FIXED JENKINS-22934] Show poll thread count option when necessary.

* Show the option when the configured value is not the default
* Show the option even when projects are in other ItemGroups
* Only consider AbstractProjects
[FIXED JENKINS-20031] Useful error message when UC not found
[FIX JENKINS-8358] Use DISABLED_ANIME icon while building
Merge pull request #1242 from daniel-beck/JENKINS-20031

[FIXED JENKINS-20031] Useful error message when UC not found
Noting #1242 (JENKINS-20031)

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>
Merge pull request #1249 from daniel-beck/JENKINS-8358

[FIX JENKINS-8358] Use DISABLED_ANIME icon while building
Noting #1249

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>
Merge pull request #1230 from daniel-beck/JENKINS-22934

[FIXED JENKINS-22934] Show poll thread count option when necessary.
Noting #1230

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>