Don't remove ccache creds before storing them

Revert #6291, which attempts to suppress duplicate credentials by
calling krb5_cc_remove in krb5_cc_store_cred.  Most of our ccache
types don't implement remove_cred, and avoiding duplicate credentials
is a responsibility better suited to the ccache implementation for
atomicity reasons.

Removing this call gets rid of the misleading "Removing ... from ..."
messages in trace logs.

https://github.com/krb5/krb5/commit/7783054742ddd807f7b2f7157d6ed81b7fb614eb
Author: Greg Hudson <ghudson@mit.edu>
Commit: 7783054742ddd807f7b2f7157d6ed81b7fb614eb
Branch: master
 src/lib/krb5/ccache/ccfns.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)