SDP-1379: Update BSW Gen6 hostname references to BSW Gen7 canonical names/examples (bos-helix-01 -> p4c-bos-01, bos-helix-02 -> p4c-bos-02, syd-helix-04 -> p4e-syd-04) in tools/bp.sh, cron.d/ReadMe.md, run_scripted_tests.sh comment, and SDP_Failover_Guide.adoc.
tools/bp.sh also gained the same Gen6/Gen7 dual-generation host-prefix branching that push_bins.sh and push_sdp.sh already had -- previously it was hardcoded to bos-helix-01/helix-0N only and would have failed outright on a Gen7 lab.
Left untouched (already correct or intentionally dual-generation): test/bsw/push_bins.sh, test/bsw/push_sdp.sh. Deferred pending a p4 edit conflict with in-progress work on tom_tyler's own clients: Server/Unix/p4/common/bin/mkrep.sh, Server/test/test_SDP.py, doc/SDP_Guide.Unix.adoc.