fetch: pass summary_width down the callchain

fetch: pass summary_width down the callchain

The leaf function on the "fetch" side that uses TRANSPORT_SUMMARY_WIDTH
constant is builtin/fetch.c::format_display() and it has two distinct
callchains.  The one that reports the primary result of fetch originates
at store_updated_refs(); the other one that reports the pruning of
the remote-tracking refs originates at prune_refs().

Teach these two places to pass summary_width down the callchain,
just like we did for the "push" side in the previous commit.

Signed-off-by: Junio C Hamano <gitster@pobox.com>