WikiPages REST endpoint always query main wiki in path based instances

Reproduction steps:

• Create a subwiki named "Foo"
• Create a page "Bar" in the "Foo": Foo:Bar.WebHome
• Access the endpoint http://localhost:8080/xwiki/rest/wikis/Foo/pages?name=Bar

Expected result:

• The answer should contain Foo:Bar.WebHome

Obtained result:

• The answer is empty or it contains result coming from main wiki if a page containing "Bar" in its name exists there

Note that this bug only impact path-based instances: domain-based instances are not impacted, e.g. you cannot reproduce the bug in extensions.xwiki.org.