Deprecate Pool param for SearchHandler

[VincentLanglet]

Subject

I am targeting this branch, because BC.

See #6307 (comment)

Changelog

### Deprecated
- Passing a Pool to SearchHandler class

[greg0ire]

The simplification in the tests feels good :)

[jordisala1991]

Shouldnt you change the xml config?

[VincentLanglet]

Shouldnt you change the xml config?

I forgot. I don't use conf anymore on my project.
Fixed.

[jordisala1991]

maybe we should add = true as default value?

[VincentLanglet]

The previous next major comment was

NEXT_MAJOR: remove default true value for $caseSensitive and add bool type hint.

So I didn't add the default true value. But I don't know why we didn't want a default value indeed.

EDIT: the default value was remove in master.

[jordisala1991]

Well then lets leave it without default

[jordisala1991]

Nice one! The Pool is only a service locator for admins? Maybe we can use Symfony directly for that. Just to think about it, nothing to change here

[VincentLanglet]

Nice one! The Pool is only a service locator for admins? Maybe we can use Symfony directly for that.

It could be great indeed to improve/remove the Pool.

For instance there is a lot of $this->pool->getPropertyAccessor() calls. We should inject the propertyAccessor directly.

There is also a $this->pool->getContainer()->get($templateRegistryId); call.

[jordisala1991]

There is also a $this->pool->getContainer()->get($templateRegistryId); call.

This one could be related with the issue we had on the Pr that adds support for sf5 on master. Not having a template registry service locator made a block on that PR