[webview_flutter_wkwebview] Skip flaky getTitle test.

[ditman]

The getTitle test is flaky (see flutter/flutter#94117).

This PR skips it, to improve the determinism of our CI.

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.
• I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/plugins repo does use dart format.)
• I signed the CLA.
• The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• I listed at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[mvanbeusekom]

LGTM

[ditman]

(Waiting for at least ios-platform_tests CHANNEL:master PLUGIN_SHARDING:--shardIndex 3 --shardCount 4 to pass)

[stuartmorgan-g]

I'd like to try #4537, and then the follow-up theory there, before disabling it.

[ditman]

#4537 is looking good.

[ditman]

Fixed by #4539