cobalt: Remove leftover dependency on //chrome/common

[rakuco]

Follow-up to #5960, which removed the dependency on //chrome/common:non_code_constants from //cobalt.

There was a leftover dependency in the cobalt_unittests target that should also have been removed.

Bug: 420684984

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[rakuco]

cc @yell0wd0g

I don't have access to the referenced bug, but it's the same one mentioned in #5960 so I'm assuming it's relevant :-)

[Awallky]

Thanks for cleaning this up!

[Awallky]

Could you add a DEPS include rule to prevent this from happening again?
See cobalt/shell/common/DEPS for an example.

[yell0wd0g]

cc @yell0wd0g

I don't have access to the referenced bug, but it's the same one mentioned in #5960 so I'm assuming it's relevant :-)

I'm known to reuse bugs for only remotely related activities, so had to open it up.
The title is "Investigate use of switches for low-powered platforms" : ) so it's
probably a catch-all. IOW it's fine to use it : )

[rakuco]

Could you add a DEPS include rule to prevent this from happening again?
See cobalt/shell/common/DEPS for an example.

Done!