framework: Fix fetch-url-list and fetch-urlall-list

The fetch-url-list and fetch-urlall-list targets are meant to produce
a list of URLs from which a port fetches its distfiles and patches.

Currently, those targets were not working as expected as they print
parts of the output meant for other targets like the fetch-list target.

For example:

mateusz.piotrowski@server /ports/x11-servers/xwayland-devel$ make fetch-urlall-list
[...]
mkdir -p "xorg" &&
-o xorg/proto-xorgproto-824001c947cb1962209c6a8f2c63c2637877220d_GL0.tar.gz
[...]

This patch prevents do-fetch.sh from printing the "mkdir" line and the
"-o" line.

While here:

• Remove the outdated comment about escaping. There is no excessive escaping happening there anymore.
• Indent cases in the case statement to match the style of the rest of the file.

Reviewed by: pizzamig
Approved by: portmgr (pizzamig)
Sponsored by: Klara Inc.
Differential Revision: https://reviews.freebsd.org/D40808