Enhanced is_edge() and is_standby() to avoid unnecessary I/O, and provided
doc of sample usage.
Updated calls to is_edge() and is_standby() in backup_functions.sh and edge_dump.sh.
Fixed issue with load_checkpoint.sh not clearing journal.NNN file when working on a
standby (journalcopy) replica, which prevented replication from automatically
starting. These files are now moved aside.
All scripts in this change now pass shellcheck compliance tests and the SDP test suite.