Fix double quoting issue when writing localconf

When [0] introduced quoting all arguments, it broke existing consumers
that already quote their value themselves. Fix this by avoiding to add
additional quotes to the value when it already starts with a double
quote.

[0] https://review.openstack.org/636078

Change-Id: I92146e04731efc6dcc632ae6c3a7c374e783cdba
Closes-Bug: 1822453
2 files changed