The bridgev2 (Go) rewrite removed matrix_mautrix_telegram_scheme (the old
Python bridge's public web-login endpoint scheme) and added a deprecation
check for it. We later reintroduced a variable of the same name to configure
the bridge's HTTP API exposure address, but the deprecation entry remained.

Because the check matches any defined variable (via ansible.builtin.varnames),
not just user-set ones, it tripped for every install with the Telegram bridge
enabled, even when the user never set it.

Drop the deprecation entry, since the variable is a current one again. The
related (still removed) matrix_mautrix_telegram_hostname and
matrix_mautrix_telegram_path_prefix entries are kept.

Closes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/5368
Regression since d2252db4fe

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>