[Cache] Fix DBAL deprecations and stop using NUL chars in tags prefix

[nicolas-grekas]

Q	A
Branch?	6.3
Bug fix?	no
New feature?	no
Deprecations?	no
Tickets	-
License	MIT
Doc PR	-

The change of the tag prefix is motivated by #49713.

The other changes are to accommodate for deprecations in DBAL.

Note that DoctrineDbalAdapter::getServerVersion() keep calling the deprecated getWrappedConnection() method because although the code says one should exist, there is no alternative way to access the server version. Drivers are all missing a getServerVersion() method (/cc @derrabus FYI)

[derrabus]

DBAL 2 is still more popular than we'd like it to be, despite being officially EOL for almost a year now. My plan was to drop support in Symfony 7. I didn't want apps to be locked on a non-LTS release because they haven't upgraded to DBAL 3 yet (for whatever reason).

I won't block the change, it's just that I think we should've talked about that. 🙂

[stof]

For Connection::PARAM_STR_ARRAY vs ArrayParameterType::STRING, we could do conditional usages of those constants, as we did in the past for the migration to ParameterType when we still wanted to support older versions of DBAL without it.
Or we could just ignore them for now (Connection::PARAM_STR_ARRAY will only be removed in DBAL 4.0, which is not a thing yet)

[nicolas-grekas]

This makes the code a bit ugly but OK, updated.

[fabpot]

Thank you @nicolas-grekas.