Bump recommended CocoaPods version to 1.8 - #52071

Description

CocoaPods introduced a CDN on 1.8 so the user no longer has to run pod setup. 1.8 has been out since September, so let's bump the minimum recommended version so users get a nudge to upgrade. Minimum required version is still 1.6.0.

Devicelab is already on higher version.

Error looks like:

Related Issues

#41491
Fixes #25592

Tests

Added recommended version test.

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Breaking Change

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