Trim lines for changelog content

[weshaggard]

We need to trim the line to eliminate extra spaces as more importantly we need to remove any extra whitespace like line endings.

[azure-sdk]

The following pipelines have been queued for testing:
java - template
java - template - tests
js - template
net - template
net - template - tests
python - template
python - template - tests
You can sign off on the approval gate to test the release stage of each pipeline.
See eng/common workflow

[weshaggard]

Closing this issue as I don't know that we want to trim the lines at this level. I found the root cause of the original issue we were hitting and it is an issue in the yamldotnet library aaubry/YamlDotNet#458 where they don't serialize a multiline string using the yml multiline syntax if there are space at the end of the line before the newlines. I think instead of fixing this here we should just fix it in the code where we are doing our yml serialization.