blocktrans in django templates should use 'trimmed' option

[qiaomin032]

Django templates support 'trimmed' option. it can remove newline characters from the beginning and the end of the content of the {% blocktrans %} tag, replace any whitespace at the beginning and end of a line and merge all lines into one using a space character to separate them.

Without 'trimmed' option, translators will get source strings with meaningless newlines and whitespace as blew:
msgid ""
"\n"
" The Email field should contain a valid email address to be associated\n"
" with the domain.\n"
" "
msgstr ""
"\n"
"电子邮件项应包括一个有效的邮件地址来\n"
"跟域名进行关联。\n"
" "
There has redundant whitespace and "\n".

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/designate-dashboard 7.0.0.0b1 development milestone.

[Tobias Urdin (tobias-urdin)]

https://review.opendev.org/c/openstack/designate-dashboard/+/532202