[Doc Bug]: fileio.ReadAll() on integration test

[svetakvsundhar]

What happened?

I am working to create more granular integration tests for dicomio.py and came across the example listed here: https://github.com/apache/beam/blob/master/sdks/python/apache_beam/io/gcp/healthcare/dicomio.py#L96

This is outdated as fileio doesnt have the ReadAll() method. What would be the recommended and updated version of this example, given the recent GCS IO migration?

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[svetakvsundhar]

cc: @shunping , @Abacn

[Abacn]

GcsIO migration should not change any beam API and user faced transform. fileio.ReadAll() seems never existed. Checked that at the commit of this comment first introduced: https://github.com/apache/beam/blob/b87bb64a44c40114779b05ab742b91cbc20e2754/sdks/python/apache_beam/io/fileio.py I did not see fileio.readAll

There exists textio.ReadAllFromText though