[fuchsia] Remove mentions of fuchsia.deprecatedtimezone.

[filmil]

The FIDL library fuchsia.deprecatedtimezone is has not been used in Flutter
for about a year now. Removing the mentions here, because the utilities
that used to provide it will be removed too, making these tests fail.

Removing the references will allow us to retire the timezone services.

Replace this paragraph with a description of what this PR is changing or adding, and why. Consider including before/after screenshots.

Fixes flutter/flutter#93003

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
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• I listed at least one issue that this PR fixes in the description above.
• I added new tests to check the change I am making or feature I am adding, or Hixie said the PR is test-exempt. See [testing the engine] for instructions on
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• All existing and new tests are passing.

[flutter-dashboard]

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 on the #hackers channel in Chat.

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[filmil]

I would not expect code removal to need any new tests beyond those already there.

[akbiggs]

@filmil That bot won't stop you from submitting.

[filmil]

Understood; just wanted to keep the comment on the record.

[akbiggs]

Gotcha makes sense.

[filmil]

I'd need some of you folks to merge this for me. I do not have commit rights.