t: make lfstest credential helper log all operations
t: make lfstest credential helper log all operations

There are current some tests which randomly fail on CI systems that
don't appear to fail on normal development systems.  To help
troubleshoot these, always log when the lfstest credential helper (which
is used in our tests) receives a command, even if we ignore it.

github/git-lfs,github/git-lfs,github/git-lfs