Remove unused SimplePrompt and DefaultPrompt functions

[pietern]

Why

These functions were added in 5ed635a (Aug 2023) for the OAuth enrollment feature but became orphaned in c3ced68 (Nov 2023) when the Databricks SDK removed OAuth enrollment.

They have been unused for nearly 2 years.

[eng-dev-ecosystem-bot]

Run: 18779831084

	Env	🔄​flaky	💚​RECOVERED	🙈​SKIP	✅​pass	🙈​skip
💚​	aws linux		1	1	319	580
💚​	aws windows		1	1	320	579
🔄​	aws-ucws linux	1	1	1	439	475
💚​	aws-ucws windows		1	1	441	474
💚​	azure linux		1	1	319	579
💚​	azure windows		1	1	320	578
💚​	azure-ucws linux		1	1	438	474
💚​	azure-ucws windows		1	1	439	473
🔄​	gcp linux	7	1	1	311	581
💚​	gcp windows		1	1	319	580

10 failing tests:

Test Name	aws linux	aws windows	aws-ucws linux	aws-ucws windows	azure linux	azure windows	azure-ucws linux	azure-ucws windows	gcp linux	gcp windows
TestAccept	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R
TestAccept/bundle/run/app-with-job	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
TestAccept/bundle/templates/default-python/combinations/classic/DATABRICKS_BUNDLE_ENGINE=direct-exp/DLT=no/NBOOK=no/PY=yes	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p
TestAccept/bundle/templates/default-python/combinations/classic/DATABRICKS_BUNDLE_ENGINE=direct-exp/DLT=no/NBOOK=yes/PY=yes	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p
TestAccept/bundle/templates/default-python/combinations/classic/DATABRICKS_BUNDLE_ENGINE=terraform/DLT=yes/NBOOK=yes/PY=yes	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p
TestClustersGet	✅​p	✅​p	🔄​f	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p
TestImportFileFormatAuto	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p
TestFilerWorkspaceFilesExtensionsRead	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p
TestWorkspaceFilesExtensions_ExportFormatIsPreserved	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p
TestWorkspaceFilesExtensions_ExportFormatIsPreserved/source_python	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	✅​p	🔄​f	✅​p