* Update matrix-domain.conf.j2

exchanged "^~" with "~" as a pattern matching in the location part.
I am very sure, that it only works using "~". I am not quite sure though, if this is the right way to do it, because "~" is probably more expensive than "^~"

the rewrite has to be behind the definition of the $backend. Otherwise nginx will fail to work. This is probably because "break" goes directly to the proxy_pass which uses $backend.

* Update matrix-domain.conf.j2

also change the order of "set $backend" and "rewrite" here in the 3pid registration section

* Update matrix-domain.conf.j2 - repeat v3_to_r0 rewrite in else-statement

as you said: repeat it for the else-case, where the ma1sd might be running on sans_container.

* Update matrix-domain.conf.j2 - corrected wrong variable

atrix_nginx_proxy_proxy_matrix_3pid_registration_v3_to_r0_redirect_enabled
is the right variable to check (twice) in the corresponding branch.

* matrix-domain.conf.j2 - fix-2954: change all whitespaces to tabs as you do it

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Co-authored-by: Tobias Küchel <t.kuechel@humboldt-ka.de>