Revert "Fix ggtags-with-current-project to include GTAGSCONF"

This reverts commit e7c5371028912e07c37de2bf1c80c88bf51a1fea.
Make ggtags-use-project-gtagsconf work on remote projects

by using --gtagsconf instead of setenv'ing GTAGSCONF which does not
work on remote projects via tramp.
New macro ggtags-with-temp-message that reports execution time