Initialise $_SERVER[ 'REMOTE_ADDR' ] in the unit test bootstrap

[johnbillion]

In various tests, $_SERVER[ 'REMOTE_ADDR' ] is given a value in order to prevent PHP notices being triggered by functions such as wpmu_log_new_registrations() which use the superglobal without validating it first.

$_SERVER[ 'REMOTE_ADDR' ] should be initialised with a dummy value in the unit test bootstrap so individual tests don't need to.

I had this patch applied while running the tests for #25162, which is why the failures were missed.

[johnbillion]

In 34172:

Initialise $_SERVER[ 'REMOTE_ADDR' ] during the test bootstrap so individual tests need not.

Fixes #33877
Fixes #25162

[johnbillion]

In 34173:

Missed files from [34172].

See #33877

[johnbillion]

In 34518:

Another missed file from [34172].

See #33877