[ACR] Retire 3 oldest preview API versions. (#28811)

* Delete specification/containerregistry/resource-manager/Microsoft.ContainerRegistry/preview/2016-06-27-preview directory

* Delete specification/containerregistry/resource-manager/Microsoft.ContainerRegistry/preview/2017-06-01-preview directory

* Delete specification/containerregistry/resource-manager/Microsoft.ContainerRegistry/preview/2018-02-01-preview directory

* Update readme.go.md

* Update readme.java.md

* Update readme.md

* Update readme.python.md

* Update readme.ruby.md

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Co-authored-by: madhura <[email protected]>

Author: sindhuselvaraj