[Android] Make temporary fix for Samsung spell checker giving blank results for all words

[camsim99]

Temporarily filters out invalid spell check results (""/ " ") received from the Samsung spell checker, since this is the result that may be returned by all words (correctly spelled and misspelled) from observation.

Temporary fix for #120608.

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• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I listed at least one issue that this PR fixes in the description above.
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• I updated/added relevant documentation (doc comments with ///).
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• All existing and new tests are passing.

[justinmc]

LGTM 👍

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Changes reported for pull request #40924 at sha 244005c

[justinmc]

Renewing my LGTM after the small change.

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Changes reported for pull request #40924 at sha c6e4643

[camsim99]

Golden file changes are available for triage from new commit, Click here to view.

Changes reported for pull request #40924 at sha c6e4643

This seems to be a flake caused by flutter/flutter#124277. Landing this PR since the tests otherwise pass.