Reduce number of queries causing : 0007463: Issue with many child issues produced performance problem

We dont need to cache bug text (steps to repro, description etc) for relationship table in which we only display summer

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@4741 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9