ktrace: Remove CAPFAIL from default trace points

The CAPFAIL tracepoint was recently extended to report ECAPMODE
capability violations for processes that do not enter capability mode.
This allows developers that are interested in Capsicumizing their
programs to determine where violations are being raised.

Previously, CAPFAIL only produced output for processes using Capsicum(4)
capabilties. Thus, most ktrace users never received log output from the
trace point. With the recent changes, this is no longer the case.

Having this trace point enabled by default will produce output for all
processes that use syscalls that are not permitted in capability mode.
This may lead to confusion for users that are not familiar with the
feature. Remove KTRFAC_CAPFAIL from ktrace's default points to avoid
this.

Approved by: markj (mentor)
Reviewed by: markj
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D44887