QUIC - Clear the server config data in QuicServerInfo object immediately
after loading or saving the data to disk cache.

This reduces the memory used by the QuicServerInfo object.

R=wtc@chromium.org

Review URL: https://codereview.chromium.org/178283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253465 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253465