This reverts commit b417370.

The change applied is no longer appropriate since the use of animations
and shadow dom components is discouraged (as of #46738)

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe: reverting a previously made change which is no longer appropriate

Issue

Issue Number: N/A

Does this PR introduce a breaking change?

• Yes
• No

Other information

• @jessicajaniuk
• As I mentioned, given the decision made in docs(animations): add section about animations and view encapsulation #46738 I think that the change I applied in fix(animations): enable shadowElements to leave when their parent does #46459 needs to be reverted to keep things clean and simpler (since we are discouraging the use of animations and shadow dom components, I don't think it makes sense to have this change in, as it just makes the incompatibility weirder/more confusing in my opinion)
• The commit message does not follow the guidelines, this seemed the cleanest way to revert the commit, but if you prefer please let me know and I will update the commit message to follow the guidelines