Remove couchbase from functionmap

[VincentLanglet]

This would
Closes phpstan/phpstan#5642

Maybe I didn't fully understood the gain of having those method in the functionMap but

• the current functionMap documents the outdated couchbase version 2.
• phpstorm-stubs correctly documents the couchbase version 3.
• there is a lot of difference between the two version (class/function removed, class/function added, lot of signature changed)

As a proof I get the correct error in my non regression test.

[phpstan-bot]

This pull request has been marked as ready for review.

[ondrejmirtes]

Thank you!

This might be an idea for a project: remove huge chunks of functionMap for things that are already nicely covered by phpstorm-stubs.

We can't remove signatures that use special PHPStan types like non-empty-string or benevolent union, but I still think we can make it much smaller. Feel free to send PRs that remove one extension at a time.