zed: fix sending emails (#12292)

Commit 6fc3099 broke the quoting when invoking the mail program, revert
that change.

Signed-off-by: Laurențiu Nicola <lnicola@dend.ro>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>