Don't check if AbortSignals tag name match EventTarget

For the v4 milestone: Revert #1001 about checking that if the tag name match EventTarget. 

_Originally posted by @TimothyGu in https://github.com/node-fetch/node-fetch/pull/1001#discussion_r550736382_