Fix policy certificate data source

[annakhm]

The data source used incorrect resource name and thus failed to
work on global manager. We switch to search-based data source
implementation.

[vmwclabot]

@annakhm, you must sign every commit in this pull request acknowledging our Developer Certificate of Origin before your changes are merged. This can be done by adding Signed-off-by: John Doe <john.doe@email.org> to the last line of each Git commit message. The e-mail address used to sign must match the e-mail address of the Git author. Click here to view the Developer Certificate of Origin agreement.

• Commit 1f3d744 must be signed by akhmelnitsky@vmware.com

[annakhm]

/test-all