When importing email in mass mailing through the form (not with an excel file),
incorrect email lines were concatenated with the following next valid email
line, resulting to an incorrect import.
This solves the problem by ignoring incorrect email lines.
Technical note: the test test_mailing_contact_import has been slightly modified
to include invalid lines in the text to import, not only at the end but also at
the beginning and in the middle (the test fails before the fix and not after).
Task-2924241
X-original-commit: bd4a933f2b3259c3482b811227de0e06c7018969
Part-of: odoo/odoo#97560
Pierre-Yves Dufays
aa0d8789d4