In each library where an import is removed, the library uses some elements
provided by the import, BUT there is another import which provides all of the
same elements, and at least one more which the library uses.

In this change, we remove the imports which can be simply removed in favor of
the other already present imports.

See https://github.com/dart-lang/sdk/issues/44569 for more information.

This stops them attempting to own a D-Bus name, which may not be possible if the
app is sandboxed (e.g. in a Snap). It's also probably what most developers would
expect is the correct behaviour by default.

This reverts commit 50a8ecb7.

* Revert "Revert "NNBD integration_test (#74922)" (#75030)"

This reverts commit 87b04365.

* fix bad merge issues

* 97646369b Remove amirh from CODEOWNERS (flutter/plugins#3484)

* 35847e473 [local_auth] Fix incorrect switch fallthrough (flutter/plugins#3473)

This reverts commit 49de01c9.