Google wants the network to be as rich as possible, the more applications and sites, the more advertising revenue for them.
No, they cannot track you using frameworks; they are retrieved once on all sites that use this URL and then cached on the client. If we say 20 sites, all links to a js file hosted on google, the user receives it only once. Hosting yourself ... if this is an intranet application, yes, do it, if not, then contact Google, slightly reduce the download time.
In addition, google has drilling agreements, the throughput is very very cheap for them.
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