[issue2551218] Remove feature flag for wsgi instance caching

New submission from John Rouillard:

2.2.0 was released with a feature flag to cache the roundup tracker
instance rather than reload on connection.

The intent is to run it and make sure there are no errors with it.

Check with Ralf to see how it is performing for his trackers. If no errors
by 2.3.0 release make it the default and remove the feature flag.

Keep the feature flag argument in RequestDispatcher, just make the
test on it go away.

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components: Web interface
keywords: Blocker
messages: 7607
nosy: rouilj, schlatterbeck
priority: normal
severity: normal
status: new
title: Remove feature flag for wsgi instance caching
type: resource usage
versions: 2.3.0

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Roundup tracker <[email protected]>
<https://issues.roundup-tracker.org/issue2551218>
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