[iOS] Fix compilation of //net on iOS.
[iOS] Fix compilation of //net on iOS.

Temporarily stop compiling //net:net_perftests on iOS as this needs to
be compiled as an application bundle (which requires first to have a
generic template to compile an application).

Stop compiling //net:dump_cache as it cannot work on iOS (applications
are sandboxed and this won't have access to Chrome on iOS cache).

BUG=459705

Review URL: https://codereview.chromium.org/1800093002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#381427}

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