Cockney rhyming is a way of substituting one word for another using an intermediate. It is done both for euphemism, and also as a cultural identity, a secret language so to speak.
In the specific case the word bottle is used to mean arse. If you don't know, arse is a British dialect form of ass -- the body part not the animal. So the originator takes the word arse which roughly rhymes with glass, and bottles and glass go together. So the phrase starts out as bottle and glass, and eventually the original rhyme is dropped, so you get just plain "bottle." The rest is implied, if you are part of the in crowd.
Often the word entirely looses the derivation. When I was growing up in Glasgow, the word "bottle" meant courage or bravado. The origins being entirely lost on us. Another example of this would be "lets take a butchers" which means "lets take a look". This was used commonly when I was growing up. The derivation being butcher's hook, which rhymes with look.
In terms of your original question, bottle means courage or bravado. As I say, when I was a kid it was used that way irrespective of Cockney slang. So "pugnacious, backbone, bottle" all live in the same semantic domain of bravado filled, fearless, courageous, belligerence.
The Einstein macro is a fake. It is an example of comedic fake quotes such as "You can't trust everything you read on the internet" - Abraham Lincoln. This quote is purely about League of Legends (abbreviated to LoL).
Essentially the answer above me explains how 'Mid or Feed' applies to LoL.
People say mid or feed to bully their team into getting the lane than they prefer to play. Mid lane is usually the lane where people can become most powerful but other lanes need to be played as well.
Saying 'Mid or Feed' is frowned upon because as a team game LoL works best when on player doesn't bully his own team.
Best Answer
In this context bottle is probably the informal BrE term for 'nerve' or 'courage'.
ODO, sense 2.
To say that someone has "more bottle than a milkman" is a jocular way of saying that he is very bold: a milkman, who delivers milk to homes, of course has a lot of bottles.