Use core24 buildd daily image

[mr-cal]

What needs to get done

1. Release and update craft-providers
2. Add support for the core24 base
3. Update spread tests

Why it needs to get done

Now that canonical/craft-providers#456 has landed, snapcraft add support for the core24 buildd daily image.

This means developers will be able to use:

base: core24
grade: devel

instead of the current paradigm:

base: core24
build-base: devel
grade: devel

[mr-cal]

@sergiusens, do we need to retain the requirement for grade: devel?

And is this the correct approach?

[mr-cal]

Currently blocked by canonical/craft-providers#498

[mr-cal]

Per Sergio, the correct approach is to not make changes to the snapcraft.yaml, but swap out the devel daily for the core24 buildd daily.

Once core24 is in beta, then we can make changes to the snapcraft.yaml.