Deprecate the usages of `DEFAULT` and `S01`

[Goooler]

Users should migrate to the central portal in the future due to the planned sunset of OSSRH.
We can deprecate the use of DEFAULT and S01 to warn users about the upcoming migration in future versions.

https://central.sonatype.org/news/20250326_ossrh_sunset/

[Goooler]

Related to gradle-nexus/publish-plugin#376.

[solrudev]

In the light of OSSRH sunset, will this issue stay a blocker for full configuration cache support after OSSRH shuts down completely?

[Goooler]

I guess these are unrelated things, off-topic for this.