chore: fallback to framework team with codeowners (#28588)

I noticed that Dependabot PRs never had anyone assigned:
https://github.com/ionic-team/ionic-framework/pull/28586

The reason was that we removed `* @ionic-team/framework` when we
adjusted the codeowners in
https://github.com/ionic-team/ionic-framework/pull/27573.

My original reasoning for why we should remove it was wrong. GitHub only
assigns reviewers within a team if the team itself is assigned. By
removing the team from being reviewed, only people listed in the
codeowners file would be assigned. As an added example, PRs that do not
match codeowners currently have no one assigned:
https://github.com/ionic-team/ionic-framework/pull/28430