Revert "kernel: adding WITH_CTF=1 to src.conf"
The option will not be picked up from src.conf according to
https://wiki.freebsd.org/DTrace

This reverts commit b225b6bbf983c2116a6a12dc8b3c58d8bc9d7239.
kernel: AMD64: enable KDTRACE_FRAME; both: Add DDB_CTF commented out
kernel: set WITH_CTF=1 when building the kernel
kernel: prepare() now enables KDTRACE_HOOKS and DDB_CTF when _freebsdver is < 10 - see the comment for details