* remove code legacy code related to deprecated config flag "trust_identity_server_for_password_resets" from synapse/config/emailconfig.py
* remove legacy code supporting depreciated config flag "trust_identity_server_for_password_resets" from synapse/config/registration.py
* remove legacy code supporting depreciated config flag "trust_identity_server_for_password_resets" from synapse/handlers/identity.py
* add tests to ensure config error is thrown and synapse refuses to start when depreciated config flag is found
* add changelog
* slightly change behavior to only check for deprecated flag if set to 'true'
* Update changelog.d/11333.misc
Co-authored-by: reivilibre <oliverw@matrix.org>
Co-authored-by: reivilibre <oliverw@matrix.org>
