Cherry-pick fixes from feature/9539_bridge_link_issue into next

Changes:

    refs #9539. Fix bridge link unit tests.

    The issue here is that new DisjointElements are being placed on the stack
    as temporaries at the time that m_parent is set. When they go out of scope
    the same address can be used in the next round of the loop, therefore all
    m_parents get set to the same value.
    (cherry picked from commit ac7fa8c6a6567cda1947328094aa2541a730aa06)

    refs #9539. Add another test
    (cherry picked from commit c4627343d6c69904e774a26703b1fbcbaf909dcc)

    refs #9539. Fix type conversion issue.
    (cherry picked from commit 6f568b0d0b649733004114f3fd22e12859f6e14f)