Revert "fetch: default to protocol version 2"

Revert "fetch: default to protocol version 2"

This reverts commit 684ceae32dae726c6a5c693b257b156926aba8b7.

Users fetching from linux-next and other kernel remotes are reporting
that the limited ref advertisement causes negotiation to reach
MAX_IN_VAIN, resulting in too-large fetches.

Reported-by: Lubomir Rintel <redacted>
Reported-by: "Dixit, Ashutosh" <redacted>
Reported-by: Jiri Slaby <redacted>
Reported-by: Konstantin Ryabitsev <redacted>
Signed-off-by: Jonathan Nieder <redacted>
Signed-off-by: Junio C Hamano <redacted>