Move cronet to framework-connectivity

aosp/2384137 added cronet to framework-tethering.
But framework-connectivity is a better place to put cronet since
cronet does not work on R devices (b/270049141) and
framework-tethering is R+, framework-connectivity is S+.

Followup CLs will move some modules (e.g. CronetJavaPrejarjarDefaults)
that use the branch dependent soong variables to framework/Android.bp

Test: TH
Bug: 278070640
Change-Id: I6bc10116759fb9e083c02147908e53022dab740a