Remove the idle_timeout option.

The option was replaced 4 years ago[1] by connection_recycle_time. The
option is not anymore present in sqlalchemy. It's the good time to
remove it.

[1] 6634218415
[2] https://review.opendev.org/c/openstack/oslo.db/+/778441

Change-Id: Id288e09688062b007d57f09aebcd7c447e56f04d

etc/trove/trove.conf.test

@@ -135,7 +135,7 @@ connection = sqlite:///trove_test.sqlite
 # idle connections. This can result in 'MySQL Gone Away' exceptions. If you
 # notice this, you can lower this value to ensure that SQLAlchemy reconnects
 # before MySQL can drop the connection.
-idle_timeout = 3600
+connection_recycle_time = 3600
 
 [composite:trove]
 use = call:trove.common.wsgi:versioned_urlmap

releasenotes/notes/remove-idle-timeout-e4a5db0d5ee524d7.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Removed the ``[database] idle_timeout`` and ``[DEFAULT] idle_timeout`` options.
+    These were all legacy aliases for ``[database] connection_recycle_time``.

trove/common/cfg.py

@@ -538,10 +538,8 @@ database_opts = [
                secret=True,
                deprecated_name='sql_connection',
                deprecated_group='DEFAULT'),
-    cfg.IntOpt('idle_timeout',
-               default=3600,
-               deprecated_name='sql_idle_timeout',
-               deprecated_group='DEFAULT'),
+    cfg.IntOpt('connection_recycle_time',
+               default=3600),
     cfg.BoolOpt('query_log',
                 default=False,
                 deprecated_name='sql_query_log',