delete old ftpmirror script, which now has security bugs (closes #23130)

--HG--
branch : 3.2
extra : source : 8f92ab37dd3a8127226bffc04d5f94b7147ba33f
merge 3.2 (#23130)

--HG--
branch : 3.3
merge 3.3 (#23130)

--HG--
branch : 3.4
make PROTOCOL_SSLv23 the default protocol version for ftplib (closes #23111)

--HG--
branch : 3.4
update docs for #23111

--HG--
branch : 3.4