Bug 26941: Fix OPAC password recovery error messages

Bug 26941: Fix OPAC password recovery error messages

In OPAC password recovery perl opac/opac-password-recovery.pl
there are some error codes not in Template koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-password-recovery.tt

This patch fixes several bugs:
- remove 'use Koha::Patrons' defined twice
- remove vars $errTooManyEmailFound $errBadEmail, not used in any template
- add in template text for error 'errNoBorrowerEmail'

1) Create a patron A with login but no email
2) Create a patron B with login and valid email
3) Go to system preferences set 'OpacResetPassword' to ON
4) Make sure that OpacPasswordChange is also ON
5) Go to 'Forgot your password' in OPAC
6) Enter login if patron A and save
=> You get message 'This account has no email address we can send the email to.'
7) Enter login if patron B and save
=> Password recovery is send, no error message

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>