Remove App.framework copy during build ios-framework

[jmagman]

Description

Remove extra framework copy and just produce the fat framework to its final destination.

Tests

build_ios_framework_module_test is already testing and validating the final copy location.

Checklist

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• I updated/added relevant documentation (doc comments with ///).
• All existing and new tests are passing.
• The analyzer (flutter analyze --flutter-repo) does not report any problems on my PR.
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Breaking Change

• No, no existing tests failed, so this is not a breaking change.
• Yes, this is a breaking change. If not, delete the remainder of this section.

[fluttergithubbot]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie.

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[christopherfujino]

lgtm

[fluttergithubbot]

This pull request is not suitable for automatic merging in its current state.

• The status or check suite Cirrus CI has failed. Please fix the issues identified (or deflake) before re-applying this label.