That commit introduced a bug to the system: f69dacf979
Restore works fine for multisite, however, stopped working for non-multisite.
Reason for that was that `establish_connection` method got a check if the multisite instance is available:
```
def self.instance
@instance
end
def self.establish_connection(opts)
@instance.establish_connection(opts) if @instance
end
```
However, the reload method don't have that check
```
def self.reload
@instance = new(instance.config_filename)
end
```
To solve it, let's ensure we are in a multisite environment before call reload
This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
