[GCPW] Update error message shown when user creation is disallowed.

Changed according to UX review.

Bug: 1068664
Change-Id: I24389f36d13b1612c79653525badca4ee6e00e9d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2140304Reviewed-by: Yusuf Sengul <yusufsn@google.com>
Commit-Queue: Robin Lewis <wrlewis@google.com>
Cr-Commit-Position: refs/heads/master@{#757203}

chrome/credential_provider/gaiacp/gaia_resources.grd

@@ -180,7 +180,7 @@
         Only the user who locked this device can sign in
       </message>
       <message name="IDS_ADD_USER_DISALLOWED" desc="">
-        Failed to add a new user. This computer only allows one user to be created using a work account.
+        Another work account is already associated with this device. Sign in with your Windows account.
       </message>
       <message name="IDS_FORGOT_PASSWORD_LINK" desc="">
         Forgot Windows Password

chrome/credential_provider/gaiacp/gaia_resources_grd/IDS_ADD_USER_DISALLOWED.png.sha1

-c7251ee2efad628f4dd7bd2d2bb88021217b99ca
+b5c424ab9800fcc350a917ad8e05d85120e903ca
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