Too strict regular expression used when searching for command groups

The tool uses predefined regular expressions to search for command groups. However, it strictly limits the expression that declares the command group should not have newlines.

Code https://github.com/Azure/azure-cli-dev-tools/blob/dev/azdev/operations/regex.py#L147-L148

Example https://dev.azure.com/azclitools/public/_build/results?buildId=135332&view=logs&j=168ccbe3-da49-5c0b-6478-08f7016e4bf5&t=10a595be-4223-5cc7-9a73-012871b6eaee&l=154