database connection retry always use default retry and interval value

Fix proposed to branch: master
Review: https://review.openstack.org/155617

Reviewed: https://review.openstack.org/155617
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=bf221170da76f73d36856d779a9b8f4840206866
Submitter: Jenkins
Branch: master

commit bf221170da76f73d36856d779a9b8f4840206866
Author: ZhiQiang Fan <email address hidden>
Date: Fri Feb 13 10:30:13 2015 +0800

    use configured max_retries and retry_interval for database connection

    We are using retrying for database connection, but that decorator
    can only have default value of max_retries and retry_interval because
    it happens at import time. We should use configured values instead,
    so this patch moves those code into inner function, which makes
    retrying get parameters at running time.

    We override max_retries for some rare case when using oslo.db, but
    that is not the right behavior. For example, collector will connect
    to metering and event databases, if one is sqlalchemy and the other
    one is MongoDB then when MongoDB lost connection in serving time,
    then the max_retries will be zero which will cause safe_mongo_call not
    work as expected. The right behavior for that sqlalchemy problem
    is enforcing max_retries when we pass it to connection __init__ method.

    Note: This patch also applies the enforcement to alarm and event
    sqlalchemy implementations.

    ref: https://review.openstack.org/#/c/127128/9
    Change-Id: Ia8bec410c1cabe850c8d033daef5a5a0ddae8954
    Closes-Bug: #1421485