Re-enable ProfileMenuClickTest-s on Windows and fix one test

Many of these tests were plagued by the TextInputServerCreate() Windows
failure (cf. crbug.com/1021930#c28, crbug.com/1123944). This has since
been resolved, so this CL re-enables the tests at least on Windows.

The CL also fixes the *SigninDisallowed* test by adding an expectation
that the "Customize profile" button [1] should be present. One would
imagine this actually regressed during the period the test stayed
disabled, but the CL where the test was introduced (crrev.com/c/1893277)
seems to imply the test was broken/incomplete all along. This justifies
changing the test and not the production code.

[1] Screenshot: crbug.com/1021930#c75

Bug: 1021930
Change-Id: I8ce40a0c07be10f14a31940d37d77c2161c5fe72
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2799632


Commit-Queue: Victor Vianna <victorvianna@google.com>
Reviewed-by: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#868514}