Fixes #26572 - Validate MTU minimum

Revert "Fixes #19731 - V2 API ping call"

This reverts commit f6de8e1da99ffb667f2c04d78ed4e6696e828c18.

Breaks Katello, too close to branching 1.22

Fixes #19731 - V2 API ping call

Fixes #26080 - Add autocomplete and date to report template (#6531)

Fixes #26020 - report templates in background process (#6503)

Refs #26253 - use correct vars in migration (#6610)

Fixes #26344 - Skip nested associations during taxonomy seed (#6587)

Nested associations can't be assigned using `${association}=`.
This causes seed to fail if there are any puppetclasses in the DB and
taxonomies were disabled during upgrade from 1.20 to 1.21.

Fixes #26260 - Mass assign discovered hosts to seeded taxonomies (#6546)

Otherwise, assignment triggers callbacks and audits for each discobered
host, leading to very long seed time when upgrading with many discovered
hosts and taxonomies disabled.
Also, don't audit template assignments.

Fixes #26253 - fix the format of serialized attributes

In a past migration hash-with-ivars objects were incorrectly converted to hash leading to extraneous elements in the hash.

Fixes #25642 - Introduce proxy registration protocol version 2