Removal of test .conf files

The following configuration files used for testing purposes have
been migrated to use the configuration fixture instead of relying
on a mechanism to load a large number of configuration options
from various locations on disk.

    keystone/tests/auth_plugin_external_default_legacy.conf
    keystone/tests/auth_plugin_external_disabled.conf
    keystone/tests/auth_plugin_external_domain.conf
    keystone/tests/auth_plugin_external_domain_legacy.conf
    keystone/tests/backend_rules.conf
    keystone/tests/test_associate_project_endpoint_extension.conf
    keystone/tests/test_auth_plugin_by_class_name.conf
    keystone/tests/test_overrides.conf
    keystone/tests/test_pki_token_provider.conf
    keystone/tests/test_revoke_kvs.conf
    keystone/tests/test_revoke_sql.conf
    keystone/tests/test_uuid_token_provider.conf

The following configuration files have had a number of elements
extracted to be used within the config fixture instead of the
configuration files. Most of these files contain controls that
need to be overridden to test against alternative (non internal /
in-memory) "live" configurations.

   keystone/tests/backend_ldap.conf
   keystone/tests/backend_liveldap.conf
   keystone/tests/backend_multi_ldap_sql.conf
   keystone/tests/backend_sql.conf
   keystone/tests/backend_tls_liveldap.conf

This patchset also consolidates the setting of the default
[database] ``connection`` option so that it can be overridden
as needed for testing against non-sqlite database engines.

Change-Id: I996709546f713c36bf654c5aea64cbf3472ffef1
Merge "Removal of test .conf files"