CTest: Fix GTM coverage handling of entry point named "%"

Removing the "%" character from the name of the routine in the line
parser causes CTest to be unable to find a routine entry point that is
only named "%".  Instead leave it during line parsing and handle routine
names ending in "%" explicitly when loading files.
Status Job ID Name Coverage
  External
passed ghostflow-check-master

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager