gh-133439: simplify how errors are reported by sqlite3 CLI

[StanFromIreland]

• Use print for file consistency
• Actually test for the full improved error message
• Correct error message, messages do not have the '.'

Request: @erlend-aasland

• Issue: sqlite3 CLI does not recognize dot commands with trailing spaces #133439

[picnixz]

I don't think this PR is needed anymore, except maybe for the assertIn

[StanFromIreland]

Should the error message not be consistent with all other cpython error messages?

I think it is still better to use print for clarity (we don't have to look it up) and consistency, all other writing in the file is done so.

[picnixz]

I think it is still better to use print for clarity (we don't have to look it up) and consistency, all other writing in the file is done so.

I guess so. I actually expected InteractiveConsole to have a write_stderr and a write_stdout but there's none, so maybe only using print makes sense. WDYT @erlend-aasland?