[chore] Add local folder to .gitignore (#12089)

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#### Description

Contrib has this folder, and I find it helpful for stashing working
files (e.g. config files) for testing running the Collector from a
binary.

Happy to take another approach if someone is doing something else to
store files used to test the Collector locally.

.gitignore

@@ -1,6 +1,7 @@
 bin/
 dist/
 .tools/
+local
 
 # GoLand IDEA
 /.idea/